Need some help diagnosing smoking engine please...
Thread Starter
Drifting
Joined: May 2001
Posts: 1,651
Likes: 13
From: Holly MI
Need some help diagnosing smoking engine please...
My buddy bought a 69 SB earlier this year, and it blows large amounts of smoke out the pipes, enough to make my eyes water following him. Before we tore the engine out, we decided to run some tests. Here's what we found:
1. Choke was not operating because it was hooked up wrong. However, the car started just fine and idled perfectly in sub 30 deg weather. (We did fix the choke.)
2. The engine pulled 18" of vacuum on start up, and increased to 20" as it warmed up. The needle did not jump around.
3. Seven out of the 8 cylinders had compression between 180-190 PSI. The number 1 cyl was 140 PSI.
4. While running, I noticed bubbles coming out of the exhaust gaskets. It looked like oil was actually being pumped through the gasket, not between it and the head.
5. The throttle was not opening all the way due to issues with the pedal and carpet.
The seller said he had the heads rebuilt, but not the lower end. Does anyone have any suggestions before we pull this engine? Any possible causes we may have overlooked?
Thanks for the help.
I forgot to add, that the engine appears completely stock. He has to add about a quart of oil every 100 miles.
[Modified by bb69, 12:10 PM 12/11/2002]
1. Choke was not operating because it was hooked up wrong. However, the car started just fine and idled perfectly in sub 30 deg weather. (We did fix the choke.)
2. The engine pulled 18" of vacuum on start up, and increased to 20" as it warmed up. The needle did not jump around.
3. Seven out of the 8 cylinders had compression between 180-190 PSI. The number 1 cyl was 140 PSI.
4. While running, I noticed bubbles coming out of the exhaust gaskets. It looked like oil was actually being pumped through the gasket, not between it and the head.
5. The throttle was not opening all the way due to issues with the pedal and carpet.
The seller said he had the heads rebuilt, but not the lower end. Does anyone have any suggestions before we pull this engine? Any possible causes we may have overlooked?
Thanks for the help.
I forgot to add, that the engine appears completely stock. He has to add about a quart of oil every 100 miles.
[Modified by bb69, 12:10 PM 12/11/2002]
Moderator
Joined: Jun 1999
Posts: 7,117
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From: Dove Mountain Arizona
Re: Need some help diagnosing smoking engine please... (bb69)
Leaks don't always come from where they appear. Could be as simple as a leaking valve cover gasket and the hot headers are making the oil bubble. Here's a question or two for you. (1) what color is the smoke coming out of the exhaust? (2) why did the heads need to be redone? (3) what was actually done to the heads? The answers will make it a little easier to diagnose. :cheers:
Thread Starter
Drifting
Joined: May 2001
Posts: 1,651
Likes: 13
From: Holly MI
Re: Need some help diagnosing smoking engine please... (MasterDave)
Masterdave,
I know what you mean, my car leaks from the breather onto the manifolds.
The smoke from his car is somewhere between blue and white. There is no indicators of coolant though, the sweet smell or problems with the oil or cooling system. I have no idea what was really done to the heads. I'm treating it a if the heads have just as many miles as the rest of the engine. The seller was adamant that he solved any oil burning problems by having the heads rebuilt, but we can see what that's worth.
Another buddy suggested that the engine could be running so rich, that the cylinder walls are being washed off, causing high wear. It seems to me the engine wouldn't pull the king of vacuum it is with this condition. Any ideas?
Thanks again.
I know what you mean, my car leaks from the breather onto the manifolds.
The smoke from his car is somewhere between blue and white. There is no indicators of coolant though, the sweet smell or problems with the oil or cooling system. I have no idea what was really done to the heads. I'm treating it a if the heads have just as many miles as the rest of the engine. The seller was adamant that he solved any oil burning problems by having the heads rebuilt, but we can see what that's worth.
Another buddy suggested that the engine could be running so rich, that the cylinder walls are being washed off, causing high wear. It seems to me the engine wouldn't pull the king of vacuum it is with this condition. Any ideas?
Thanks again.
Melting Slicks
Joined: Apr 2002
Posts: 2,103
Likes: 0
From: Tucson AZ
Re: Need some help diagnosing smoking engine please... (bb69)
3. Seven out of the 8 cylinders had compression between 180-190 PSI. The number 1 cyl was 140 PSI.
I forgot to add, that the engine appears completely stock. He has to add about a quart of oil every 100 miles.
[Modified by bb69, 12:10 PM 12/11/2002]
Thread Starter
Drifting
Joined: May 2001
Posts: 1,651
Likes: 13
From: Holly MI
Re: Need some help diagnosing smoking engine please... (Robert N)
The car smokes pretty much anytime it's running, but it gets worse under hard acceleration and deceleration. To me, this would indicate rings, but for that much oil to come out one cylinder, I would expect the reading on that cylinder to be far worse than the #1 cyl was.
Melting Slicks
Joined: Apr 2002
Posts: 2,103
Likes: 0
From: Tucson AZ
Re: Need some help diagnosing smoking engine please... (bb69)
The rings could be bad on all of the cylinders with the #1 causing most of the loss. You could also have bad valve seals. You mentioned that the heads were rebuilt but that does not mean well or that the seals simply deteriorated. That would dump additional oil into the cylinders. You mentioned the bubbling. If the gasket material is cork (porous) and oil was being compressed in a cylinder, it could be forced out as mentioned through the gasket.
I am not the expert here, just following a course of logical and unfortunate personal experiences!
I am not the expert here, just following a course of logical and unfortunate personal experiences!
Melting Slicks
Joined: Jul 2001
Posts: 2,609
Likes: 12
From: Massapequa Park NY
Re: Need some help diagnosing smoking engine please... (bb69)
I had a similar problem with my 390 mustang after a complete rebuild. Thought it was rings but it turned out the valve guides were shot. Had the heads rebuilt & guides replaced twice too. Only found the problem after changing to a different machine shop. Turned out the valve stems were tapered ( .003" )causing the guides to fail almost immediately on initial startup. The first machine shop said they were fine & recommended against replacement :mad
Pull one of the heads & pop off the springs. You should not be able to feel any side to side movement in the valve.
Of course you might want to check the simple stuff first :lol:
PCV valve, breather element, make sure the valve covers are baffled, etc.
Pull one of the heads & pop off the springs. You should not be able to feel any side to side movement in the valve.
Of course you might want to check the simple stuff first :lol:
PCV valve, breather element, make sure the valve covers are baffled, etc.
