How to confirm smoke caused by valve seals? - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 10 (permalink) Old May 26th, 02, 08:53 AM Thread Starter
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Ray
 
Join Date: Sep 2000
Location: Central FL
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I have a smoking problem that I'm trying to diagnose. My engine smokes on occasion when I crank it up. Big embarassing puff, then stops. I've also been told that it puffs slightly each time I shift from someone driving behind be, but not enough for me to see in the mirror.

Thoughts are: valve guides/seals, PCV, or intake leak. The heads (Trick Flow Twisted Wedge) had new bronze guides and seals intalled less than a year ago to try and fix this problem, so hate to think its them. Changed the intake gasket recently, but smoked before and after, so don't think that is the problem. The rubber hose between the PCV valve and intake had oil in it, so I assumed that was the problem. I replaced it, but the engine still smoked as before. Just to make sure the PCV valve wasn't the source of the problem, I disconnected it and plugged the port at the intake. Still smokes.

So I'm back to suspecting the valve seals or guides. It smoked before I had them replaced, and I thought that would solve the problem but it didn't. I hate to think the shop that did them screwed them up, but it is very possible. They put two spring seat cups under one valve spring and none under another that caused the spring to bind and pull the rocker arm stud out. I helicoiled the stud and corrected the seat cup problem myself. So they've already screwed up once. But I hate to accuse them of screwing up the guide or seals without reasonable proof.

So, how can I prove to myself that the guides or seals are the problem? I've inspected them visually, and see no obvious problems. Is there anything else I can do to confirm where the smoke is coming from. Is there anyway to confirm it's not the intake leaking? I'm certain its oil, as I have no leaks but keep having to add oil. And I don't lose any coolant.

Again, its smokes a big puff sometimes when I crank it, but not every time. And it smokes a small puff when I shift.

And yes, I know it sounds like guides or seals. But I want to know if there is anyway to confirm this without pulling the heads, before I accuse the head shop of screwing up.

Thanks for any ideas,



------------------
Ray

68 SS Convertible
Corvette(77) Yellow
383 w/DFI Fuel Injection
on MiniRamII intake,
Trick Flow heads
Tremec 5 sp, 3.31 12bolt Posi
Guildstrand Mod
AGR 12:1 power steering
Bent short steering arms
Baer 13" front brakes (Couldn't find time to make my on bracket)
550# Hypercoils with Landrum height adjusters

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post #2 of 10 (permalink) Old May 26th, 02, 03:27 PM
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i cant think of a way to tell for sure if its valve stem seals sure sounds like it especialy if its only on cold starts. as far as the shifts did you use a windage tray on the bottom end. also did you have a fuel problem at start up that could have given you ring wash. accusing a shop never leads to anything but headaches especially when you have worked on them your self. if its runnin great and not fouling plugs an they all look great ok but if a couple look different then start there to diagnose or look for a crushed seal or guide. good luck
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post #3 of 10 (permalink) Old May 27th, 02, 08:21 AM
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Here's my take. Yep....it's the seals...it's the only source that will cause oil contamination in the chamber via down and over the valves. What kind of seals are you using?

The puffs between shift tho sound like a little may be getting past the PCV on shifts. Usually, a little oil is present in the tubes, but plug it up and see if it goes away. How many miles do you have on this engine? And, have you done the coast down test from let's say 50mph and shift into a lower gear and close throttle to see if the puffs continue?

One more question....are you using a high volume oil pump?

This will help diagnose the problem.

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STEVE JACK
ConceptOne Pulleys and Brackets
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post #4 of 10 (permalink) Old May 27th, 02, 12:52 PM Thread Starter
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Ray
 
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Storman: I have no windage tray. What exactly happens with ring wash, is this something from the initial startup, or every startup? I don't think it starts rich, but it could be. I'll have to recheck that. The only work I've done on the heads myself since the new guides were installed, is remove the doubled up seat cups, add a new seat cup to the adjacent valve on the same cylinder that was missing one, and helicoil the rocker arm stud that was pulled out. When I informed the owner of the head shop of the problem, he was very apologetic and gave his son, who did the job, a very good natured ribbing about it. I pulled all the plugs, some have oil on them, some don't, done are fouled out.

HOTRODSRJ: The valve seals are umbrella syle rubber seals, I was told not to go with teflon for the street(?). The engine has about 20,000 miles on it. It doesn't smoke when I accelerate, so I don't suspect any ring problems. I currently have the PCV disconnected to test that, and it still smokes. I've done the coast down test, and I can't see any smoke behind me, but I didn't have any one to follow me at the time, so don't know if it smoked a little or not. I will check that again with someone following me.

Thanks for the replies,

Ray
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post #5 of 10 (permalink) Old May 28th, 02, 06:42 AM
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i was wondering about the ring wash which is a large amount of fuel from a bad carb or malfuntioning fuel injection washing the oil off the cylinder walls during initial startup taking away the hone etc. but i think your on the right track with the valve seals an such. especialy with the cylinders that have oil on the plugs.
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post #6 of 10 (permalink) Old May 28th, 02, 07:02 AM
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Jeff
 
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Do you have roller rockers or roller tip rockers on this motor?
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post #7 of 10 (permalink) Old May 28th, 02, 08:29 AM Thread Starter
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Ray
 
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Ratpack: Yes, Comp Cams Magnum steel full roller rockers.

Ray
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post #8 of 10 (permalink) Old May 28th, 02, 03:37 PM
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Ray-

Hear is an idea. Are you noticing the start up smoke on cold temp days more so than warm temp days?

I ask because, on some fuel injection systems, during cranking (to stat the engine)the computer will fire all the injectors at the same time creating a rich condition to assure good starting in cold temps and all temps. Depending on where the motor stops after it is shut down, will determine if raw fuel gets dumped through a wide open intake valve. Sometimes you'll get a big puddle sitting in there and a nice puff of smoke on start-up when the fuel in that puddle burns. Once the fuel in the puddle is burned off...nor more smoke.

I state this theory because you said that it smokes onhly on occassion when you start it up...not every time. usually valve stem seal leaks produce smoke on start-up almost every time.

I'm not an Accel DFI expert but Ive worked with some fuel injection systems and the smoke from rich mixtures during start-up does happen. Its hard to notice on newer cars beacuse of the catalytic converters.
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post #9 of 10 (permalink) Old May 29th, 02, 02:25 AM
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Jeff
 
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Ray, my engine builder told me the roller rockers MAY cause some oil usage due to the amount of oil it dumps on the valve stem. I put new valve seals on my 350 and it still pushes some oil by the seals. He told me high volume oil pump and roller rockers will use some oil. Not sure how true that is.
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post #10 of 10 (permalink) Old May 29th, 02, 05:30 AM Thread Starter
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Ray
 
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What are the best valve seals to use for a street engine, as for as service life and oil control?

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