928 GT R

I find it interesting that almost every car on BAT gets debased now for needing a top end refresh. I am fortunate to have just purchased a 94 GTS with incredible service records.

Timing belt replacements in 2000, 2007, 2014 with all appropriate components replaced. Oil changes with no mileages over 3,000mi. Coolant changes every two years with one exception of 2014 - 2018.

Some owners really walk the walk when it comes to servicing these cars and have the means to do so. Occasionally cars of this nature come onto the market. This GT might well be one of them!

hlee96

Dennis,

Why not put this beauty on BaT? Your track record there is so good.

Very nice car buddy.

https://sfbay.craigslist.org/eby/cto...739437325.html

Mrmerlin

FWIW a intake refresh is done on a time basis.
IE the electric parts just crumble no way around it,
lack of use or storage is not going to remove this fact it will delay the replacement time .
Any S4 or later will need this done.

The powder coating is usually refinished as well due to age,
as its usually got corrosion under it and will flake off with some provocation.

The throttle shaft bearings are now made with double seals so installing these will let the engine run with less intake leaks,
the original bearings with single seals have hardened O rings so they leak.You will replace 4 of these bearings.
Same for the cam cover gaskets they are hard if original, and possibly oozing oil.

NOTE the oil block off pins might need to be replaced in the heads if the updated pins were not installed during production.

A newer set of 4 hole fuel injectors will make the engine run better.
As well as a new set of Beru ignition wires
Might be time for a silicone OPG when the MMs get done, cant see with the belly pan in the way.

This 91 GT looks like it has been in a time capsule the exterior and interior present Excellent in the pictures, this is usually a quality the aftermarket can not reproduce.

That said, from what I see, this car will need an intake refresh and motor mounts, trans mounts and a fresh set of Bilstien shocks and bumpers.
I would install a Greg Brown slave flex line and fuel lines if not already done.
Buy a new factory belly pan and remove the NACA ducts and put them on the pan currently installed.

The washer tank looks like its been rusting so the collars should be removed and maybe add a new fill spout without the collar fitted,
and flush the washer tank and lines out so you dont spray rusted fluid all over the hood.
Check/replace the 3 way junction as well since you will be in their.

NOTE my observations are made with the idea that your your going to drive the car and enjoy it.
This is one of the best GT machines Porsche ever made and it happens to have been kept in Excellent condition.
The parts I suggested to replace will restore the lost performance that time/ useage have taken.

hlee96

I agree that every 928 should have an intake refresh to make them feel brand new as long as the owner has unlimited funds and don’t care about money. However, the 928 market is not there yet to warrant every 32v 928 to require having an intake refresh just due to age when it may drive perfectly fine without any problems.

We are not debating if this 928 should have an intake refresh when it needs one, but if it drives nicely and nothing is screaming that it truly needs one except for age, bashing it with the thought of it not deserving its value would only keep this car undervalue for the foreseeable future. If the brakes, transmission, coolant, fuel lines, power steering lines, and typical important service items are addressed, then the lack of a “formal” intake refresh should not be the huge weakness that it was pointed out to be. If a buyer can afford this car as is, when it comes time for an intake refresh, more likely than not, he/she can afford the service.

I enjoy my 928 to an extend that i wanted it to be kept in nice shape with fuel lines, wp/tb addressed, and of course the typical oil/coolant/brake services, but if you will require me to have everyone of them “turn back to new” just due to age and not due to some driving deficiency, then I can guarantee you the model will forever be kept undervalued due to others’ requiring it to be so.

Example: for this particular '91 GT, if it was advertised at $25k on autotrader from a local BMW/Mercedes/luxury car dealer as a trade in used car, would anyone NOT rush to call in and reserve it immediately before going to see the paint/interior either in person or hi-res closeups photos? However, if everyone feels that a 32V 928 shouldn't be sold/bought without an immediate intake refresh that can easily go from $15k-30k (especially with Stan's suggestion to have all shocks replaced, mounts, and GB clutch lines, etc), no matter how nicely it drove during test driving, etc, that $25k "bargain" wouldn't be so "bargain" anymore and the car will end up sitting and selling for $15-20k. Is this what we want as a community?

I am not advocating selling junks/lemons to unsuspecting car fans, but to say every car needs an intake refresh/mounts changes/lines replaced (with exception of fuel/power steering) before being sold is just silly.

Then it’s just my opinion

longrunner1

Truth be told, in total Agreement with your assessment Stan,, just got done with a 1988 S4 consignment, addressing your educated expertise of what they need always, especially if you want to drive them and enjoy them as they were meant to be.The S4 ran like a champ with doing the Intake Refresh,lots of great responsive power, and handled and rode 100%. better after doing Motor mounts and Tranny mounts and suspension parts.Value of car just increased by 10k- 15k.

hacker-pschorr

I agree 100%, well said.

Often times we get a bit carried away on this topic and need to remember these are not vintage V12 Ferrari's and never will be.

Most of us can do a proper TB / WP job in a day or long weekend. A 100% proper intake / cam cover refresh is a big job and not necessary unless something is leaking or causing an issue. Frankly the #1 reason most cars need a refresh is to fix the flappy actuator (that's what my car needs). My 87 needs this work and frankly I have so many other irons in the fire, I'm going to pull the intake, replace the actuator and put it back on. I know long term a full refresh would be better, but other than the flappy the car runs like a top. My time / $$ will be better spent on other project, the full refresh can wait, a long time.

928 GT R

Stan,

I enjoyed your thoughtful and experienced comments as always. My observation is simply that sometimes the intake refresh may have already been done.

Your NOTE leaves collector/drivers like me in a bit of a quandary... I am attempting to be efficient in the servicing of my growing collection...

In the case of head gaskets, I'd like your advise because of your long term and in-depth experience, but first a little background.

20 years ago I was privileged to look inside the engine of an otherwise nice Euro Twin Dizzy. I had just purchased my first S4 5-speed. Drooman was my service advisor and pointed out that the coolant had been neglected in the Twin Dizzy and this was why the heads were being removed. He showed me the corrosion and utter corruption in the cooling system. It formed the basis for my religious flushing of the coolant systems on a bi-annual basis regardless of mileage. My cooling systems all get G-05 and Distilled water with Red-Line water wetter only. At various opportune intervals I have even filled/flushed the coolant systems with pure distilled water and taken the car out for a spirited drive, dumped the distilled water again and then performed the G-05 fill. I recall being advised to change the head gaskets in my exceptionally well maintained 928 S4 several years before selling it. The next three owners never had a problem and the car is now lost to follow up after well over 300,000 miles without an intake refresh or head gasket re-fresh.

The last time I did a WP/TB on my 90 GT outlaw, the cooling system was exceptionally clean, in fact, cleaner than when I purchased it in 2002. My cars are stored in a low humidity building where the temp never drops below 50 and seldom rises above 80.

This begets the question: "Do all 928's need their head gaskets replaced after a finite time period regardless of their maintenance?"

If the answer is in the affirmative, I would need to schedule myself to do it when I do my next intake refresh instead of waiting for corroded heads and the nightmare of welding new metal into the probable defects. It also means that I have to become a far more informed/skilled mechanic because there is no-one locally available to do this work. My most intrusive work has been the oil pan/motor mount job with the hands on help of Jim Doerr who graciously travelled to my "ZOO" garage.

How does this relate to the FOR SALE thread? In my opinion there are very few 928 owners that are ready to tackle an engine out head job simply because their car hits 20, 25, or 30 years of age after already tackling the intake refresh and oil pan motor mount projects. If the recommendation is that all S4 or newer cars need head gaskets at a specific time interval, it only makes sense to defer the intake refresh, oil pan gasket refresh, WP/TB job until that calendar date and do everything at once.

IMO, that is going to put a whole bunch of cars on the market because if you can't lust after these beauties without seeing a "find a 928 specialist and pull the engine" maintenance bill on top of the purchase price, it is game over for most owners and would be purchasers.

So again, what is the head gasket time interval for a 928 S4, GT or GTS with a "perfectly maintained" cooling system?

Thanks again for all you do and your enormous contributions to this forum.

Dave


P.S. if this post is inappropriate for the "For Sale " thread I will be happy to remove it.

Ninespub

Well stated!

Mrmerlin

This discussion might be better served in its own thread but I will answer these concerns.

Do all 928's need their head gaskets replaced after a finite time period regardless of their maintenance?"

IMHO if the coolant is changed every 5 years ,
and distilled water is used with the fresh coolant.
and cooling system inspections and service are done.

AND the engine appears to operate as it should with no running hot temps,
then the gaskets can be left alone till a time when indications they might need to be serviced occur.
This will apply more to the 32V engines .

For 16 V cars, since they are quite a bit older
the cooling systems have a higher probability that they have not been serviced as well as a later 32 V engine might have been.
So the chances are higher that a 16 V engine will need new HGs VS a 32 V engine

That said my White 88 had water installed into the cooling system and it sat for 2 years before I was able to inspect it and fix it,
This entailed removing the heads and replacing the gaskets
My clues that things were amiss were just water coming out of the cooling system and large amounts of rust with the water,
then the rebuilt water pump and all of the rust it had.

Hoi About the servicing of S4 series machines, the important thing to realize here is that these are very well built machines,
and they can suffer many issues before the car simply will not run.

That said if you want a nice 928 thats been serviced and known wear issues repaired on a time based service interval,
then with the expectation that you could hop into the car and drive from Philly to California and back to Philly with no issues ,
Then it would be wise to follow my suggestions.

If on the other hand your buying a 928 to drive to the car show and CnC once in a while,
then if its running OK you might as well not make the cash investment.

I think this is really a question of how the machine is going to be used by its current owner.
As a mechanic I will fix it to drive it with the thought that as many of the time wear issues have been serviced and updated,
so the car can be a reliable daily driver for its owner.

As a collector /owner you have the luxury to buy and fix whats needed or not,
it still does not change the fact that the car needs these system to be refreshed to get maximum performance/enjoyment from the car.

Most of the 32V cars I inspect now are needing the full intake refresh, as well as shocks and mounts
once an owner finds out what the cost is to return the systems to new condition,
thats usually the tipping point for them to sell the car while its still running good,
though it will usually have a bouncy ride and loose feeling suspension and a tired looking engine bay.

IMHO The best thing anyone can do with a nice 928 is make sure its fully serviced,
and that the wear items are replaced even if they are working.
For example shocks and motor mounts,
I dont know how many times I have replaced shocks and motor mounts on a customers car ,
only to hear them say how wonderful the car now rides with new shocks and how smooth it is with new mounts.
It should have been the first thing I fixed....

Eric you would be wise to have a new crank position sensor and 2 knock sensors to install with your Flappy pod,
and since you have the luxury of a garage, to put your car in till its fixed
you should consider replacing the flappy and throttle shaft bearings so to reduce the air and oil leaks the originals will have.

Also you could then inspect/replace the TPS,
As a test take it off and place its open end face down on some paper towels in a warm area for a day, let the unit sit in the sunshine
if the rag is soaked with oil you should replace the TPS and the shaft bearings.

FWIW the usual failure for intake removal that I have found are crumbling knock sensors and CPS wiring ,
in the many intakes I have done,
only one had a failed Flappy pod.

NOTE many are missing the 19MM flappy stop,

NOTE this stop being missing can let the flappy plate bind into the intake and stay stuck closed.

Here is a nice detailed S4 intake refresh written by Dave C.
This will give you an idea of what has to happen .

https://www.google.com/url?sa=t&rct=...Gs6JyUKI7Rg2Gx

buccicone

I must concur. If it aint broke don't fix it! It is always good food for thought though.

worf928

If every 928 offered-up came with a thorough expert PPI then we'd have a market with near-perfect information. But, this is not stable nor something that is consistent with human nature. The Latin Caveat Emptor is where all human-operated markets have a stable point.

Yup. This entire subject boils down to expectations and goals.

That depends upon expectations and goals. And of course the exact state of 'this car' which can't be determined by pictures alone.

Exactly. It is human nature - and thus the nature of all markets 'run' by humans - to attempt to produce information asymmetry. And this asymmetry usually favors the seller and not the buyer.

If a seller doesn't have high-confidence that an expert PPI will turn up virtually nothing on an otherwise presents-well-in-pictures 928 there is only downside risk.

Furthermore, ...

... the upside for the seller is not something that is obvious in the 928 market.

Furthermore, your concept that an intake refresh costs $15k is a bit fanciful depending upon your definition and outcome expectation. That figure is a very significant fraction of the expense of an engine-out cad-re-plated factory-fresh restoration by anyone that knows what they are doing on 928s. .

Are you sure your GTS doesn't 'need' an intake refresh? Does it pass a Hammer Check of all the various intake-related bits that can be tested? Have you reviewed all the service records for intake-related replacements? If the WOT switch or flappy vacuum-actuator was busted would it 'need' an intake refresh in your mind? Or are you fine driving it with those issues?

Obviously, we must frame the term 'need' in the context of expectations and goals.

It might be. The risk is to the buyer though. And the magnitude of the risk is dependent upon expectations and goals.

Right. I pretty much agree with everything Stan writes.

Let's, now, attempt to frame 'need' in terms of goals and expectations.

If you are buying a 928 and your goal is to keep it in the garage, drive it a couple dozen miles per month, at most, and buy it as a piece of art with an eye towards preserving it's value as an investment then 'need' is defined (IMO) as

a) something that would show up in pictures when you sell it or be very obvious on a short test drive.
b) scheduled maintenance of the sort most non-928-savvy folks expect needs to be kept up-to-date.

Basically 'need' in this context is something broken that prevents the car from being driven or obvious maintenance way out of date. A 928 rarely driven doesn't leak much. Most folks don't know that '90+ 928s need PSD flushes. Heck, even most 'car folks' seem to think that flushing hydraulics every 2-3 years or coolant every 5 years is a waste of money.

(My) Bottomline: the bar for 'need' is very low for investment grade 928s. The owner's - IMO - are most interested in minimizing maintenance expenses over the life of their 'investment.' They don't care if the oil pan leaks a bit, or if a busted Hall sensor is pulling 6 degrees of timing, or if a carboned-up GTS is knocking on full throttle. It doesn't have to operate 'as well as it could or should.' It just needs to operate sufficiently to not be obviously in serious need.

This works, to some extent, as long as information in the market remains asymmetric (i.e. buyers don't know what they don't know) and the car in-question doesn't break too often.

On the other hand, if your goal is to enjoy your 928 as often as possible - thousands of miles per year - then the definition of 'need' expands.

If your goal is to have your 928 running as it should run then the definition of 'need' expands.

If your goal is to have your 928 NOT nickle and dime you to death then the definition of 'need' expands.

If you goal is to not have your 928 broken and waiting in line at a shop (or waiting for your free weekends) 50% of the time then the definition of 'need' expands.

It is these goals that drive the type of 'system maintenance/restoration' that you find me/Stan/Greg/Sean/et. al. recommending for folks who's goals seem to be *driving* it rather than throwing money at it.

Let's take the intake on 'that '91 GT. It was bolted together 28 years ago in Zuffenhausen. If we assume that the intake has remained untouched since then...

There is a time-based guaranty that at least one of the following is true (and I probably skipped some...)
- The CPS is going to die soon due to connector disintegration. (No start.)
- At least one knock sensor is causing an EZK code due to connector disintegration. (6 degrees of timing.)
- The vacuum actuator for the flappy is dead. (10% of top-end power gone.)
- The rear fuel return line is cracked from dry rot and is about to start dripping fuel when it flexes (after the dead motor mounts are replaced to fix the vibration problem....)
- The injectors are varnished-up and have a poor spray pattern or are leaking when 'off.' (Poor/unsteady idle and/or poor power throttle response, and/or poor starting behavior, and/or poor power.)
- The WOT part of the WOT/idle switch is dead. (Poor WOT power, increased knock risk.)
- At least one under-intake breather line is about to separate. (Massive oil leak.)
- The oil filler neck leaks (Progressive oil leak)
- The big o-ring for the water bridge is leaking. (Progressive coolant leak (onto timing belt and rollers.))

Now, we ALL KNOW that EVERY SINGLE ONE of these failure modes WILL occur. There is no doubt. At all. It's just a question of when and in which order. Most of these are time-based failure modes due to materials degrading. Unless the car was stored in a nitrogen bottle.

If you replace the WOT switch how long will it be before the oil filler neck starts leaking badly? After you've replaced the oil filler gasket how long before the bridge starts leaking profusely? Then the flappy stops working and now - since the knock sensor code was pulling 6 degrees of timing - you notice that this 928 really doesn't feel very fast at all. So, you replace the flappy actuator.

Your intake has now been off four times and you've pretty much spent the money for an intake refresh but are only half-way done and your 928 still doesn't run like it should and the intake coating still looks nasty.

I know I've seen this type of progression with at least one recalcitrant 928 owner. I'd be surprised if Stan/Greg/Sean hasn't seen this happen at least once also.

I'm responding to these posts in order and reading as I go...

... so! Yup. Expectations and goals. Driving it. Minimizing cumulative expenses and in-shop time and maximizing the time you can spend driving it. AND minimizing the 'worry factor' about what's going to break next.

And, unless the owner has experienced a 928 with it's stock level of performance, there can be dozens of things wrong that each rob a few foot-pounds and the owner will never know.

This statement only works in the context of garage queens. In the context of driving a couple (or many) thousand miles per year, downtime, and *cumulative* expense is *minimized* by taking a 'systems' approach to maintenance and paying for common labor once.

We have to define 'perfectly fine.' A 928 can have tons of engine problems and still go down the road with some alacrity. You can have a non-functioning WOT switch, dirty injectors, out-of-spec MAS, leaking water-bridge o-rings, bad hall sensor, knock sensor codes, and breather hoses puking oil under crank case pressure and a 928 will still drive pretty OK if you don't have another to compare it against.

If find this *particularly* true for GTSs. Due to the oil-ingestion-mess with GTSs any GTS that hasn't had the pistons de-carbed is missing a ton of top-end power. They still run pretty good. Lot's of low end torque. It feels faster than a GT (but isn't.) The knocking above 4k RPM is silent. And since the owners haven't driven a 'fresh' GTS they don't realize what they are missing above 5k rpm (which BTW, is a f@#$ing eye-opener.)

First, I have no problem with waiting to do a full intake refresh until there are several things wrong. I have in fact counseled this approach (except for fuel lines.)

IMO, every '87+ 928 owner that wants to enjoy their 928 as much as possible, should be aware that at *some* point in their future the full intake service will be required - or, at least, that a full intake refresh will be the most cost-effective approach if they have long-term ownership goals.

OR.... changing the asymmetry of information in the market might actually make 928s with recent full refreshes of various systems worth more.

Wouldn't this be a benefit to all 928 buyers and sellers? If information asymmetry can be reduced then even the 'investment grade' buyers have upside: If, during their investment period, sufficient under-intake mayhem ensues then they have ROI on a full intake refresh. It's risk protection.

Brakes, transmission, coolant, and power steering lines are not directly related to the intake refresh.

Coolant changes is a basic periodic service requirement. Brakes are usage and transmissions require scheduled fluid changes (Rogerbox more so along with filter.) All that is just basic scheduled maintenance or replacement of items that wear directly with usage. Nothing to do with an intake refresh. The power steering lines are only a teeny-tiny bit easier to do with the cam covers off.

And if by "typical important service items are addressed" you mean that all of the intake-related failure modes I listed above have been addressed (according to the records) then sure, an intake refresh isn't going to be an imminent service risk.

Back to expectations and goals and whether or not a driving deficiency is discernible (i.e. buyer lacks information.)

The Ferrari market doesn't work that way. And yeah, I know "Ferrari blah, blah." It's still just a car. A Ferrari's needs to keep it operating as-designed are fundamentally the same as the 928. (Except that the 928 doesn't have buttons that turn to glue like Ferraris...) There is no objective reason that the 928 market couldn't work that way. What prevents it from working that way - besides perception of value - is information asymmetry. There seems to be a lot less of it in the F-car world.

This (redacted for space) is the kind of statement that underscores the concept of information asymmetry. You are, essentially, predicating that prices will only increase as long as buyers are ignorant and no one spends money on 'system level' maintenance. Furthermore, you also seem to think that with better information in the market that 928s with recent 'intake refreshes' wouldn't be valued anymore than those without.

This last point - are 'restored' 928s worth more than kinda-limping-along 928s - is a market characteristic I'm interested in observing. I don't know the answer. So, far, I think the answer is no. For a lot of reasons.

Last, I think you conflate 'intake refresh' with full mechanical restoration. An intake refresh is not a $15k-30k proposition (except perhaps at Beverly Hills Porsche...) $30-$35k will get you a complete mechanical restoration on a good quality mid-high mileage 928 (like the '91 GT in question.) If it's got 120k+ miles and you want 'upgrades' or if it's been seriously beaten-on or stored in a swap then it's more.

And very last, my observations are that market prices for all 928s have increased in the last 10 years while the average condition has decreased. A 50k-mile GT expected to go for $50+k in 2018 was a $25k GT in 2008 and both have the same issues except that that GT 2018 is leaking a bit more. LOL.

It's definitely not silly if the buyer's intention is to drive the 928 a lot. It's only silly under the assumption that the 928 isn't going to be driven or if the buyer is very-far from a perfectionist and/or will never know what they are missing.

It IS silly if you are selling to another 'investor.'

This -^ is interesting data. How objective is it?

This works for you because you are assessing the risk of needing to pull the intake again within a certain time period with full knowledge of your '87's condition and some knowledge of its history. And, of course, the fact that it's YOU doing the labor.

Someone paying a shop for labor to replace the flappy would be taking a much bigger risk.

Absolutely. It may have been done. If there are no records of it being done then you need to look deeper if you are worried about it. It's not hard to determine if there are 'issues' under the intake. If there are no issues, then drive the p1$$ out of it until there are enough under-intake issues that you've decided 'it's time.'

It's sad that records of service get 'lost' so often.

GT6ixer

Mrmerlin

Nate if possible,capturing a picture of the car would have helped,
the listing is gone.

linderpat

drscottsmith