ACE1252

I wasn't expecting to see that. I was expecting to see the needle pulsate(for head gasket issue), but to see it climb and hold pressure pressure like that does make me think you are right on having some type of head gasket/head/block deck issue....especially for it to go so high.

For those without Facebook...
http://www.ace1252.com/videos/219898271372111_50880.mp4

Hopefully some others will chime in on it. I need to go look at some material that came with my pressure tester. I'm hoping that something in the water pump system might cause this or as another said...the cooling system somehow sucking air from somewhere(other than cylinder pressure causing it).

ACE1252

The manual for my pressure tester suggests pulling the spark plug wires for one cylinder at a time to find a head gasket issue. Now, this is with the needle vibrating issue. They are looking for the needle to stop vibrating when you find the offending cylinder.

I'm not sure how a 350 will run with one cylinder out(shaking and such). You may need to pull two wires two keep the engine balanced when revving it. Pull 1 and 6, 8 and 5, 4 and 7, then 3 and 2.

I've never had to pull wires on my 350 to troubleshoot issues yet, so it would be best for others to chime in to see if what I'm telling you is correct course of action.

ACE1252

Still bothers me that it's acting like a check valve.....

With the engine stone cold, can you pressurize the system to around 12-15 lbs. and see if it holds that pressure for more than 2 minutes?

ACE1252

This dude is named Eric too and he does have a decent vid on cooling system diagnosis....he actually has quite a bit of good stuff on his youtube channel.

[autostream]http://autostream.com/camaroz28/?page_type=firebirdplayerthumbnail&framepage=1017& transactionid=1306106666-174111107140&posted_by=ACE1252_www.camaroz28.com&y outube_video_id=hUzOTnsWImI[/autostream]

Edit....be sure to watch the video at the 21:30 minute mark on!

adam85

Yes you can. It should hold for a long time. Why only test at 12-15lbs? It should be tested at the rad cap pressure.

ACE1252

Oh, hehe, I was asking the OP to do it.

It really gets hard to pump up the pressure tester after around 12 lbs. The manual for mine is very specific to say not to exceed the cap pressure. So I dared not to go near it if possible. In my experience, I've never needed above 10lbs to find a problem, but I've only worked on a handful of cars with cooling system issues.....so that is not a high sample to go by.

MyFastTA

Thats the thing that puzzles me, its like it the seal can hold x amount of pressure before it bleeds off anything over that pressure but has never allowed any coolant into the cylinder. The only other way I can see to determine a cylinder would be to remove plugs and try to pressurize cylinder with shop air. Not sure I could get enough pressure to find the problem. I just pulled one valve cover to just check a few head bolts to make sure did not somehow back up but they were still torqued. I did get arp head bolts so I am not for sure. I actually am a mechanic I have just never seen anything like this. Oh and yes that cooling system will sit holding pressure easily overnight, it has started a small seap at the waterpump gasket which I will replace gaskets when I determine the problem. I know this was a wierd one and just seeing if anyone has ever heard of or seen anything like this. All milling and decking done at excellent machine shop not making much sense. I did go with the thinner gasket for a little more CR I am just really dreading doing those heads again IMO it would be easier to just pull front cradle.
Thanks for all advice
Bryan

ACE1252

I didn't know you were an auto mechanic....you've for certain seen more than I when it comes to car issues.

I'll be thinking more on this overnight, but I might could offer one more piece of advice.

My factory manual states to crush up two cooling system sealing tablets and add to the coolant when the system is drained and refilled(GM part#3634621). I have always done this, over the years, with no trouble whatsoever. It might be worth trying to see if it seals up.

I know that it could be applying a band aid to the problem....but it's something that GM felt was needed during servicing. The package states that its used to prevent leaks due to casting porosity in engine components....used for both iron and aluminum blocks.

I assume that you are going to do the coolant combustion gas test like at the end of that vid I posted. I'd be interested to see how that comes out. I'd do the diagnostic stuff before attempting to see if the tablets can seal it. That way you can try to isolate to a cylinder. Have you done a leak down and/or compression test yet? if not, I'm sure it's on your list of things to do.

MyFastTA

Ya I did the chemical test today and tried it a couple different times. Sometimes it would stay the blue color. One time it turned green but im not sure it might have gotten a little bit of coolant into the tester. The chemical should turn yellow if is mixed with hydro carbons so im not sure if I contaminated the chemical or it detected fuel. I have never used those tablets it is a idea. I have worked on tons of cars but I rarely get a f body at the shop it must be people that have these cars either like to work on them themselves or they take them to performance related shops? So there is a lot I can learn that is specific to these cars. I believe the leak down test is next on my list to do...I guess I have to try to pressurize cylinders and look for bubbles in the radiator

ACE1252

That sounds like a good plan.

MyFastTA

I guess I have just come to the realization I need to just replace the gaskets and check the heads I have been dancing around it but I need to just go to the source of the problem. Although I will be going with standard thickness head gaskets instead of the thinner set. Hopefully I can get it most of the way done tomorrow. Ill keep ya posted on how it is after new gaskets.

MyFastTA

I finally got a little time and got one head off it is the passenger head. It was for sure the gasket leaking compression I was able to take some pictures in case it would help any one. I still have to get the other side off and see what it looks like but I imagine the gasket also leaking compression. I guess those thinner mr gasket head gaskets wont hold up to high compression. It has been 15 miles and probably a hour to hour and a half of run time. I got Cometic head gaskets now so I will no longer have this problem and I did check the torque on all bolts and they were all accurate. I have checked the head with a straight edge and it is straight as can be.


.....I am just glad I figured out the problem and will soon be able to enjoy it...and yes the car was running quite rich for about the first 20 minutes of engines life until I got the tune

adam85

Good to know you found the problem. I'm sure it will be tearing up the road soon.

MyFastTA

yes sir hopefully have it back togeter sunday

ACE1252

Glad to hear your found the problem. I used Felpro 1074's when I put my engine back together.