928autobahndreamer

How often is it recommended to redo the intake seals and all of the associated sensors. I was just going through old maintanence record for my shark last night and found a receipt I had missed earlier. This included intake removal, gaskets, injector seals, knock sensors, and vac lines. The reciept showed a date of 10/2000. I know one of the vac lines has come off from under the intake and was thinking about going in and redoing everything.

I guess my question is, should I bother redoing all of this, or can I just lift things up enough to re-attach the vac line and leave the rest well enough alone as it was all redone less than 15K miles ago?

rixter

unless you have other issues, fix the vac line and leave it alone

RyanPerrella

everything should be fine. I think most people replacing all this stuff are doing it on original equipment. Think 20 year old stuff. 5 years is nothing. Replace just the line or just reconnect it. Spend your time and money on other parts and other projects.

Or if your intake is cracking and needs to be repainted then you could do it. But at that point i would replace only the intake gaskets and the gaskets in the manifold. You dont need to do knock sensors again or anything like that again.

the flyin' scotsman

I'm doing mine as we type but I'm very sure its the first time since the factory put the engine together.............wouldn't being going in unless I had to.

There are 3 vac lines under the intake; not sure how you'd re-attach without lifting the intake then your disturbing many gaskets and fuel lines at which time you may as well look at the entire assembly. You must have a large vac leak.

worf928

+1

At 7 years and 15k miles if the rubber isn't still good then you've got other issues.

I did an intake R&R on my '91 when it had about 32k miles in 1998 to replace the flappy actuator. At 7 years the rubber was still rubber and the only other things I replaced was the knock sensors and injector o-rings. Now, almost 10 years later and 50k miles more, it is time (and has been for the last year or two) to do the Full-Intake-Monty.

My GTS's rubber bits are still in OK shape but many are showing signs of sweating and I'll bet that within the next two years it'll need the Full-Intake-Monty.

No data on my '89. I started pulling it apart the moment it was in my garage as it came with no service records.

So, based upon my two data points I'd say you need to replace all the rubber every 15 years.

928autobahndreamer

Thanks for the replys. I was origionally going on the assumption that the intake had never been done. So, I was planning on doing the whole shebang including powdercoating the intake manifold. However, now that I find it was done I think I will just leave well enough alone. I have plenty of mechanical issues I can be spending money on without blowing a $1000 on the intake.

I had 2 lines off that attach under the TB and I managed to get my hand far enough under to reattach one of them. The other is still not attached. Is it worth disassembling the intake for the other line to be attached? The car is running well. The only thing that I see as a problem is that the smog pump air diverter is running all the time (I think this is the feed for the line that is off) and my heater is on all the time. I have already replaced the heater valve and as many other vac lines as I could get to. I still need to attack the vac lines and diaphragms under the dash.

As a side note, looking at the reciepts from the prev owners, there is no way I could afford this car without RL. Intake R&R $3000, Timing belt and assorted minor fixes $4400, Steering rack $2500, AC repair $2000 on two separate occasions. Not to mention the little fixes here and there that were $100-300 a pop. I have put quite a bit of $$$ into it so far, but it has all been parts. Most of the above is labor.

So, thanks again for everyone here.

JHowell37

I think that most people do it because many of these cars are well over 20 years old and have had little or no maintenance of that nature under the hood. But think about it, if the original stuff lasted for 20 years, the new stuff will probably last as long as well. How many of us will own these things in 20 years?

928autobahndreamer

I'm hoping more than one

the flyin' scotsman

As mentioned there are 3 vac lines that attach to the tbody; 1 for the charcoal system, 1 for the air pump diverter valve and 1 for the 5 way splitter that supplies vacuum to the 2 dampers, regulator and auto transmission. Of these 3 the I'd be concerned re. the 5 way splitter, the charcoal system then the air pump system..........that order of priority. In saying that these are primary vacuum sources and any leak or opening in the system must result in serious vac leak to the fuel system and should be corrected asap.

On another recent thread when comparing pics I noticed the '87 tbody has 2 vac ports on the underside and one on top...........my '88 car is opposite.

Pics are of my '88 tbody:

928autobahndreamer

I am pretty sure I was able to get to all of the vac connections except for the vac line to the air pump diverter. Will running the car with the vac leak for this cause any damage to the car? The only thing I can notice at all concerning performance is mabe idle running just a touch fast approx 775.

I may try wedging my hand under there again to see if I can get that last connection done without having to pull the intake. I got one, how much harder can the second be?

worf928

I don't think so. But, it might cause your car to ...
... idle a bit high. You will also have just a bit of extra unmeasured air entering the motor when you go to WOT. But, as most 87+ 928s run wicked-rich at WOT a little extra air isn't a bad thing.
'Wedging things in there' can have unintended consequences. What you may be able to do, if your intake gaskets and the 10 pressure gaskets for the intake buts are still rubbery is to loosen the intake just enough to lift it up an inch. That might be enough room to get your hand under. Disconnect the fuel rails, remove the 10 intake bolts. If you''ve got enough slack in the harnesses then you can, at that point lift up the intake and stick something between the intake and intake ports to keep it up. If you don't have enough slack then you'll need to start disconnecting connections.

Mrmerlin

you should be able to refit the vacuum line, BUT you might have to go to the extreme of putting a thick blanket on the engine and laying on top of the engine and with the new set of Harbor freight 15 assorted needle nose pliers and an inspection mirror and a drop light , refit your hose, you may also have to remove the hood (for Head clearance) but I dont think thats necessary

Mrmerlin

you should be able to refit the vacuum line, BUT you might have to go to the extreme of putting a thick blanket on the engine and laying on top of the engine and with the new set of Harbor freight 15 assorted needle nose pliers and an inspection mirror and a drop light , refit your hose, you may also have to remove the hood (for Head clearance) but I dont think thats necessary, Remove the air cleaner and MAF first

StratfordShark

I've just started doing mine today, but I'm almost certain this is the first time the intake has been off on a 20 year old car. 7 years should be fine for all the hoses/gaskets, but the problem is you need to do just as much work to fix that single vac disconnection you have.

mj1pate

It is absolutely remarkable how long the rubber breather hoses last. I'm confident that the vacuum hoses and breathers under my 86.5 intake were original, at the time I replaced them. The plastic vacuum hoses were still servicable, although the rubber elbows had heat-expanded so as to be leaky. The breathers were still doing their intended function, although had become hard and brittle so as to be virtually inflexible. When squeezed by pliers the breather hoses broke apart like porcelein. Needless to say, all rubber was replaced during the servicing. This is also a good time to replace all rubber fuel hoses and the crank position sensor.

The 85/86 MYs have ISVs that can be reached and reaplaced without removing the intakes, *as long as* the attached breather hoses are recent and flexible. I did not replace the TPS on mine, as it was functioning correctly, although intake-off work would be necessary to replace it, should it become necessary. Watch out , as one of the original 85/86 breathers attaching between the main air tube and the oil filler neck has an imbedded PCV valve. The replacement hose did not.

Mike