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1990 Pontiac Sunbird LE Smokes after valve job

Sent to Car Experts July 10, 2006 1:27 p.m.

I was recently given a 1990 Pontiac Sunbird LE Convertible with a 2.0L OHC engine. I was told that it was blowing white smoke and that there was no compression in the 4th cylinder. I was also told that the car had been given a new engine (or possibly rebuilt, I'm not sure), but the rebuild was taking too long, so the previous owner's daughter got another car and the wife drove it. However, she overheated it and the smoking started. So initial analysis was probably a blown headgasket or a warped head. I'm not a mechanic but am reasonably handy with tools (and a trusty Haynes manual).

I pulled the head and took it to a machine shop. They reported back to me that there was a burnt valve, but that the head did not need machining as it was within .001" of true. I had them do the valve job and a pressure check (which it passed).

I carefully reassembled the engine with a new headgasket kit and new bolts. However, it still smokes.

I tested the compression and all cylinders show 135psi, but there is oil on the #4 spark plug. I also tested the intake manifold with a vacuum gauge and it shows a steady 12 inches of vacuum. My manual says this is low and I may have missed the timing belt by 1 cog. Also, I am in Denver, so the altitude affects the vacuum.

As I said, I am not a mechanic, so I can't say that the smoke is blue or white - or maybe a combination of the two.

Any ideas of what I can look at next?

Thanks in advance

Optional Information:
1990 Pontiac Subird LE 2.0L OHC

Already Tried:
Rebuilt head and had valve job performed. Tested compression and vacuum.

Customer (name blocked for privacy)

Status: Closed Value: $15

Answer
July 10, 2006 1:39 p.m. (11 minutes and 11 seconds later)

REPLIED

Possibility that you have a cracked block in the cylinder wall area. If its a coolant smoke then it should be a white smoke and you should notice the loss of coolant. It could be oil consumption and that will be a more of a bluish color and according to how bad it is there will be a black souty build up in the tail pipe. I am more leaning toward the cracked cylinder problem due to the know overheat problem.

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Thanks Tim

Tim Basham -- OutBack Auto 4wd &Fab -- 100% Positive Feedback on 271 Car Accepts
25 year multi line tech ASE cert master tech ASE engine machinist. Specializing in 4WD +++

Reply to Tim Basham
Sent July 10, 2006 3:19 p.m. (1 hour and 40 minutes later)

Well, because of the smoking and not wanting to do unnecessary further damage, I have driven it only around the block, so not enough to notice coolant loss.

Is there no way to test for a cracked block? It would seem that the cylinder compression in the bad cylinder would be lower, wouldn't it?

Again, thanks for your help.

Customer (name blocked for privacy)

Answer
July 10, 2006 4:31 p.m. (1 hour and 12 minutes later)

ACCEPTED

a cracked block can be real hard to diagnosis due to the fact it doesn't normally effect compression because it is below the compression rings and they do make a testor to check for combustion gases in the cooling system but it will have to be a fairly bad leak for it to pick it up. The thing is with a crack it can be like a one way valve and only happen when hot.

how bad is it actually smoking ? a cloud blocking everything behind you or just enough that you can see it. Have you ran it long enough to get it up to running temp if so is it worse hot or cold.

__________________
I hope I have been helpful. If more info is needed just ask.
Please select Accept when your question has been answered. And Bonuses and Feedback are nice too.
Thanks Tim

Tim Basham -- OutBack Auto 4wd &Fab -- 100% Positive Feedback on 271 Car Accepts
25 year multi line tech ASE cert master tech ASE engine machinist. Specializing in 4WD +++

Reply to Tim Basham
Sent July 10, 2006 4:58 p.m. (26 minutes and 24 seconds later)

When the engine is cold, there is just a light whisper of smoke. At idle, as the engine warms up, the smoke increases to a pretty think cloud - enough to worry about the neighbors complaining!!! Then, driving it around the block, the cloud of smoke is enough to worry about getting a ticket out on a more public street - or getting yelled at by the driver(s) behind.

I didn't know / think about the crack in the block being below the rings, but that makes sense.

Thanks for your help!!!

Customer (name blocked for privacy)

Answer
July 10, 2006 7:46 p.m. (2 hours and 48 minutes later)

REPLIED

Glad I could be of help. Sorry I couldn't give you a better answer but sometimes there just isn't a good answer.

__________________
I hope I have been helpful. If more info is needed just ask.
Please select Accept when your question has been answered. And Bonuses and Feedback are nice too.
Thanks Tim

Tim Basham -- OutBack Auto 4wd &Fab -- 100% Positive Feedback on 271 Car Accepts
25 year multi line tech ASE cert master tech ASE engine machinist. Specializing in 4WD +++

Reply to Tim Basham
Sent July 11, 2006 9:48 a.m. (14 hours and 1 minute later)

Tim,

I don't mean to drag this out, but of course I get lots of suggestions from people about what the problem could be.

Does the Sunbird have a Transmission Accumulator Valve and what would be the symptoms if it were leaking?

I've taken the car to a mechanic - time for me to stop messing with it.

Thanks for your help.

Gary

Customer (name blocked for privacy)

Answer
July 11, 2006 11:10 a.m. (1 hour and 22 minutes later)

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Tim Basham -- OutBack Auto 4wd &Fab -- 100% Positive Feedback on 271 Car Accepts
25 year multi line tech ASE cert master tech ASE engine machinist. Specializing in 4WD +++

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