What are Costs to rebuild a 1994 3.6 turbo motor

[slfergy]

I have a 70k mileage motor that has a 74% leakdown in #1 & 3 cylinders- intake valve, the rest are 3% to 7%. It still runs very fast but I'm afraid to not fix it due to screwing up a head or worse.
1.) How much does a complete top end cost?
2.) How much does a complete bottom rebuild cost?
3.) How much to replace the clutch while the top end is being done?
4.) How much to replace the clutch when doing the bottom?
I'm talking stock parts or oem.
5.) How much does it cost to change the gear ratio of 1st thru 5th gears in the trans?
I don't need to go 180mph but want to go to 140 really fast.

It would be nice to add new cams and rebuild the turbo for some extra juice but I have to find out what the options cost first.
Stacy Ferguson

[Drdogface]

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[noporsche75]

Well i may be a noob but i suggest a search also I'm sure its all realtive to what all is damaged and needs replaced.IF the sleeves and stuff are fine i imagine it woudlnt be all tha tbad but from what ive read once stuff like that gets damaged price goes up substantially

[mb911]

74% leakdown but yet still runs fast?? Not likely.. probably not all that bad on the leakdown.. recheck

[cstreit]

Originally posted by slfergy
I have a 70k mileage motor that has a 74% leakdown in #1 & 3 cylinders- intake valve, the rest are 3% to 7%. It still runs very fast but I'm afraid to not fix it due to screwing up a head or worse. Stacy Ferguson

Take it out once and run it hard for a few minutes to make sure you don't have carbon flaked off and not allowing the valve to seat. What made you do the leakdown in the first place, did you overrev? Notice a substantial power loss?

If you do have that kind of leakdown, definitely get it fixed. Bent valves can break off and destroy the engine right quick. The turbo's can run quite strong with that sort of leakdown and worse!

Lets assume that the leakdown is right:

1.) How much does a complete top end cost?
2.) How much does a complete bottom rebuild cost?

I just did one of these recently. Bottom end on these is about 50-60 hours (dealer gets 60 hours per Porsche IIRC). A top end is probably in the 35 hour range (more if there are larger issues/upgrades). Parts costs usually come close to labor amounts so you can figure it out from there based on your chosen shops rate. Here in Chicago dealers get $125/hr. Independent shops like mine charge less.


3.) How much to replace the clutch while the top end is being done?
4.) How much to replace the clutch when doing the bottom?
I'm talking stock parts or oem.

Add in probably an extra half-hour plus clutch cost. everything's already out. If the flywheel needs resurfacing or other stuff going on, possibly a bit more.... Bottom end is the same. Engine already out.

5.) How much does it cost to change the gear ratio of 1st thru 5th gears in the trans? I don't need to go 180mph but want to go to 140 really fast.

Gearsets these days are running $600-$650 a gear IIRC. So figure you'd change 2-5. That's $2400-$2500 in parts plus the labor cost of the trans teardown and rebuild with new gears.

It would be nice to add new cams and rebuild the turbo for some extra juice but I have to find out what the options cost first.

While you're in theres are the best parts. ...and end up costing as much too. There's no better time to do them though. Be sure that you actually NEED the top-end before embarking on this process. PM'd you my number in case you want to talk.

[slfergy]

I want to thank each and everyone of you for your feedback.
What caused me to have a leak down was an old friend who used to build and race Porsche cars and it was his thermometer so to speak. But he could pull and rebuild a motor in one or two days back in the 60's or 70's. Simple engines and cars back then.
I went out to Blackhawk Farms race track in Rockton, Illinois with the PCA driver's ed track day and It ran well, Rick at Fisher Motors in Barrington drove it and said it didn't feel like the leakdown was accurate and he seems to be considered a top notch Porsche guy in the Western Chicago area.
So I'm kind of in la la land trying to figure it out.
Thanks again!

[Matt_West]

Given the amount that hangs in the balance on this issue would it not make sense to retest? Hopefully you can find a second person to do a leak down, don't given them any background and see what the results say.

[cstreit]

Stacy,

I'd definitely recheck it, the "feels good" is not particularly telling especially in a turbo motor. Fischer does know their stuff but obviously one cannot diagnose much just by driving. I recently drove another turbo with 80% leakdown on at least 3 cylinders and it ran great, felt really strong, but had a bunch of bent valves.

If some valves are bent, this presents a dangerous situation for you. They don't get cooled properly because a lot of the cooling happens as they sit on the valve seat, they are prone to breakage, particulaly in a turbo. Broken valve = very bad things including damaged piston and head for sure, damaged cylinder, rod, and crankshaft is possible.

If you're running Blackhawk, you may be close to me, let me know if I can help.

[fastfredracing]

My 930 has better than 80% leakdown on one cylinder , and even though it idles like %#$@!, when the boost boost, it actualy pulls real hard on all 6 cylinders. I guess when you cram all that air in there even a partially dead cylinder will fire.

[cstreit]

Fred,

Be sure to find where that leakage is occuring. If it's past the rings you're probably not in a great deal of danger. If you have a bent valve, you very well may be. As I mentioned above, the head of the valve is cooled by contact. (By the valve stem and the valve seat) If it is not coming into contact with the head, less cooling can mean overheated and broken valves.

In addition the bent valve is probably getting distorted as it closes. This repeated stress can also accelerate breakage of the valve.

You can use the "rubber glove" test while doing the leakdown to help pinpoint the leak. Put a rubber glove over the intake, exhaust, and case breather. Hook up your air supply and really crank it up. Observe the gloves.

[Wayne 962]

It used to be about $6K to do something like this yourself, or about $8K to have someone else do it, but the parts have increased in price considerably with the fall of the dollar. I think it's quite a bit more these days, if you replace everything...

-Wayne

[fastfredracing]

That rubber glove test is a great trick, I have never heard of that one. The leak is coming from the head gasket, as the car has a couple of busted studs. No worries, I am not driving the car, it is in the funds aquisition stage. I drove it on the day I purchased it, and after the leakdown test about 200 yards just to get it back into my garage.

[euro911sc]

Originally posted by cstreit
You can use the "rubber glove" test while doing the leakdown to help pinpoint the leak. Put a rubber glove over the intake, exhaust, and case breather. Hook up your air supply and really crank it up. Observe the gloves.

um... doesn't the rubber glove on the exhaust melt? Leak down is a hot test right

Best regards,

Michael

[cstreit]

Michael,

Yes, hot is always preferable, but an exhaust tip cools down pretty quickly...

...and in the case of a car with bent valves, it doesn't matter HOW hot the engine is..