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I am going to suggest that Worf’s response above and all of the embedded quotes that reference everyone’s thoughts and experiences be reworded to take out any specific car references (eg the particular ‘91 that is in question) and be put into the new member sticky for others to reference.
I have often wondered if there would be any value in separating the new member sticky into a “maintenance and operation” sticky and a separate “buyers guide”.
just thinking out loud
-Scott
I agree. This is some of the best and most constructive discussion I've ever read on RL. Great stuff from everybody!
That is a beautiful car, and I don't even really like blue interiors. My opinion is it is worth every penny under 60K. And I don't think all this discussion about maintenance detracts from the car any.
I agree with Stan and Dave basically. Personally, I am more focused on the expectation side. Any car I have better be ready for an almost guaranteed trouble-free 1.000 mile road trip. My 90 GT is garage queen investor grade car, my 91 GT isn't. Both are in top shape and have had and continue to get all such work done to them to meet this expectation.
Most investors however will not require that an investor garage queen type car fulfill such expectations as I have. For these people, no need for 100% reliability. So putting off a top end refresh won't hurt anything (unless the heads are Swiss cheese). Good records for coolant changes go along way to get rid of that worry.
Thanks Stan. I really need to update that. It's been 15 years since I wrote it
Originally Posted by 928 GT R
Stan,
This begets the question: "Do all 928's need their head gaskets replaced after a finite time period regardless of their maintenance?"
You more-or-less asked just Stan this question. But, I'm going to throw my $0.0928 into this.
The most-basic and correct answer to your question is: Who knows?
It's pretty reasonable - to me at least, for many reasons - to assume that Porsche wasn't thinking about service schedules for 20- and 30-year-old 928s in the 1970s when they were designing the 928 motor. The youngest 928 is now 23 years old.
I doubt any of the folks that work on many 928s can or would answer that question without paragraphs of caveats and explanation. All that can be done is to pull heads, consider the chemisty, service records, and head condition and form theories about the expected lifetime of head gaskets under various conditions.
And, to make it even more interesting, it's not the head gaskets we are worried about. It doesn't matter how nasty the gasket is as long as it is sealed. And the gaskets - as far as leaking is concerned - work well.
It's the condition of the heads that we are worried about.
Coolant reacts with aluminum. The heads are aluminum. The additive packages in coolant are - in part - included to 'get in front' of the chemical reaction between coolant and aluminum. With no additive package heads wouldn't last very long at all. Once the coolant additive package is gone due to time, there's nothing to stop corrosion. If coolant-induced corrosion is enabled to proceed without hindrance eventually the surface of the head around the cylinder walls 'goes away' and no head gasket will seal that hole and thus the 'head gasket pops.'
There's no way to stop the corrosion completely. It's going to happen. All we can do is slow the corrosion by ensuring that the head surface is always in contact with coolant that still contains the additive package. And thus, there's no simple answer to the question. There are only 'best-guesses' based upon theories and available-for-a-specific-928 data. If there is NO data on coolant changes then the very safe guess is: the heads are swiss cheese and the gaskets could pop at any moment.
Why do we worry about head gaskets popping? If the corrosion gets bad enough to allow coolant into the cylinder(s) it can cause a 'loss of motor' situation. It doesn't always. But it can.
Why don't we just run'em until the head gasket pops? For the obvious reason that there is a small and fixed supply of replacement heads. And a small supply of replacement blocks. And if you are looking for the later heads or blocks then the supply is even smaller.
A swiss-cheese head can be fixed. Even a 'popped' head can be fixed. I learned a lot about this last April due to necessity. Aluminum corrosion in heads is 'fixed' by welding-in new aluminum. Aluminum castings do funny things when they get hot spots from welding.
The cost to repair is - in the best case - proportional to the extent of corrosion and in the case of a 'popped' head the cost probably (I don't know, not BTDT) goes parabolic (based on discussions with my 'head guy.) 'Fixing' these heads when they are close-to-done, is by the way, only accomplished, correctly, by really experienced folks and the cost is mostly their expert labor hours.
In terms of cost, if your heads are 'about to pop' - corrosion is within 1mm of one of the head's fire rings - the cost to correctly, expertly, repair at set of heads to a ready-to-bolt-on state can be $2.5-$4k. At an (rough) estimated $4k repair cost, you might as well get used heads from Mark and have your 'head guy' do a basic refresh. Of course, that assumes that you have an '88-89 S4. The ceiling is about $500 higher for '89+ and all that assumes Mark has some in stock.
If your gaskets do pop due to head corrosion, I don't have a notion of the cost to repair. I would though worry about needing to be bring my 'head guy' both heads, both block pieces and the crank and cams.
Keep in mind that those cost notions above are with the heads stripped and in your hands. Add to that the cost of getting the heads in your hands and then putting them back in.
So? Why do we worry about head gaskets? We don't. We worry about head corrosion and trying to save heads (and blocks) from the scrap pile.
And no, I didn't answer the question. Yet. But, I'm done for at least today.
Hoi....83' Euro 5-speed in Wallingford https://www.ebay.com/itm/1983-Porsch...0:pf:0&vxp=mtr
So sad: "I purchased it with the intention of restoring it with my son. However, my son was recently diagnosed with brain cancer which forces me to sell #JohnnysFight"
"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."
~~~~~~~~~~~~~~~~~~~~~~~
Dave C., I will venture answering your questions:
1. "Am I sure my GTS doesn't need an intake refresh?" Given the 2014 documented receipt, I am as sure as I can be.
2. "Does it pass a Hammer Check out of all the various intake-relates bits that can be tested?" I do not know as I do not have a Hammer Tool.
3. "Have you reviewed the service records for intake related replacements?" Yes... The intake and TB/WP were refreshed in 2014 and I have the service records totaling $6,910.99.The intake was not powder coated, apparently to preserve originality.
4. "Or are you fine driving it with those issues?" The car performs exceptionally well and I would need a track to test any need/capacity for higher performance. I've driven 928's in excess of 200,000 miles and hopefully have a good baseline on performance levels.
The maintenance on my GTS was thorough and consistent through its well documented life. It is not a concourse prepared car, but even PSD flushes were regular and documented.
My needs, expectations and goals are to have fun driving and displaying these rolling engineering masterpieces, maintain them efficiently, and own an appreciating asset that I quite simply... enjoy having around me.
Again, many thanks to Worf, Mrmerlin, linderpat GT6er, Shawn Stanford and all the others who contribute so much. This has been enlightening!
I looked at this couple weeks ago. Guy who owns it does not know much about the car. Car starts but does not run. I tried different fuel pump relay and then noticed that someone had already tried fuel pump jumper.
The car is a repaint in gold and looks to be mokka original paint. decent paint job. but done long ago.
Car mileage is pretty accurate, the tires have 3 digit date code prior to 2000 and have lots of tread on them . Car sat at house where current owner cut the lawn. owner died and he offered to store the car when house sold. then decided to buy it. Missing air cleaner set up. very original. Pasha is very nice except on passengers seat where there are burn marks. Pasha is Black/Brown. Guy is getting divorced and needs to sell the car. It will need to be towed.
Probably needs complete fuel system cleaned out at min.
Has front S spoiler and rear "87 spoiler.
House where it came from had 2 older corvettes ('56) and older 911.
11-04-2018, 11:35 AM
