DeWolf

After a long intake intake refresh (about 18 months) I buttoned the car up the other night, changed some leaking injectors and she ran like a champ. Idling in the driveway last night about to put it in the garage and I noticed the idle change to a lumpy mess. Done a few things toady and then done a compression test. Number 7 cylinder 50psi, all the others 160psi. I'll get a leak down tester and see where it's going. Bugga!

Edit; Can the heads come off while the motor is still in the car?

zekgb

Nope, gotta pull the engine to get the heads off unless you do some machinations to get the studs out. Do a leakdown test to see what's going on. Crossing my fingers for you, but totally feel your pain (literally.)

DeWolf

Just need to get my manual going now and then start on the auto. Oh well, good way to keep the mileage down.

FredR

Scott,

Did you do a powder coat job on the intake?

Rgds

Fred

DeWolf

Hi Fred,

Sure did. Have I missed something?

FredR

Scott,

I very much hate to be the bearer of potentially bad tidings and I sincerely hope my concerns prove unfounded but there is a history of problems when folks have done what you have done in that the blasting media gets trapped in the nooks and crannies inside the inlet manifold where it is hard if not impossible to see. Doubtless the outfit the doing the coating will be aware of the need to remove the media but [most likely?] are not aware of just how difficult this is with this kit and consequently something gets left behind. At some stage invariably shortly after commissioning a dollop of blasting media lets go from its hiding hole and beds itself inside a cylinder or cylinders . Quality control for complete removal of blasting media from the internal surfaces is the most critical part of the coating process and particularly so for your model.

I sure hope this is not the case and wish I could suggest something else might be the problem [not impossible to be clear] but when what you describe happens immediately after a powder coat job the probability of something else happening is not in your favour most sad to say.

We recently had a similar case on a 86.5 motor owned by Mr Vanster- lookup threads he generated in the advanced search option. Seems this model is particular prone to this happening by nature of its geometry. The damage was incredible- I could hardly believe what he experienced.

Please keep an open mind until the cause of your problem is proven to be the case and let's just hope it is something less dramatic but your compression numbers tell a corroborating story [assuming your compression test technique is correct]. Please confirm you had the throttle butterfly open for all cylinders when you did the tests - that you had seven consistent results and one duff one again suggests you did the test correctly but...? Was the motor warm when you did the test? Tests of this kind and leak down really need to be done with a warm motor for maximum reliability but it sure looks ominous when seven are the same and one is way low.

Again I stress the importance of verification of what has happened before accepting such has happened- at this stage the intent should be to eliminate such possibility from the list of potential candidates.

Rgds

Fred

DeWolf

Fred,
Engine was up to temp and the plenums were off so in essence, wide open throttle. There is all of a sudden a hell of a lot of oil in the intake. I thinking its broken rings or a trashed bore or piston. I made sure I cleaned the intakes out thoroughly. Bought a toilet brush and modified it to scrub down the insides. I'l; keep the updates coming after the leak down.

FredR

Scott,

If you are seeing this oil for the first time then it certainly sounds as though something is seriously amiss whatever the cause.

Do you have access to a borescope- not that I am sure it will tell you what you need to know. Also take a look at Vanster's recent thread. There is quite some detailed posting about measures taken to ensure cleanliness after blasting.

In the meantime please keep an open mind about other possibilities until the root cause of the problem is ascertained. Random failures can and do occur [sad to say] even though the evidence is mounting as it were.

My thoughts with you at this telling time and sincerely hope you have a good [$$ painless] outcome.

Rgds

Fred

Imo000

Nope, you can pull the heads with the engine in the car (regardless what the repair manual says). I've done it twice. No it isn't easy but it is doable. Look for my thread on this from many years ago. The driver side is the tricky one, passanger side comes off without much drama.

zekgb

Even if I could get the heads off somehow, knowing what it took to get the block prepped to put the heads back on I'm not sure how I would have had any chance to do it well in situ.

DeWolf

I'm thinking that as well. Might as well re-ring it etc while I'm there.

FredR

Scott,

This is the thread I referred earlier:

https://rennlist.com/forums/928-foru...rebuild-6.html

Rgds

Fred

Imo000

You said it isn't possible.

Bambalam

Scott
Any chance this is a head gasket problem rather than bore damage - maybe the length of time sitting has caused gasket failure. The oil in the manifold could be a problem with the breathers - one way valve problem or just attached to the wrong connection.
Run through some less major issues first.

Imo000

The benefit of pulling the heads with the engine in the car is if you have limited working space. You can store the removed parts in the trunk of the car and essentially only need room for the footprint of the car.