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My Triumph

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A_1974_TR6__

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I bought this car last year, was smoking a little, previous owner told me worn valve guides was the reason for the smoke. I replaced the guides, and had the valves and seats re-ground . Now the car smokes like its on fire. But if I take it for a highway drive the smoke stops. Compression seems good, 115 to 140. ANy ideas??
 
Oil smoke (blue), rich mixture (black), coolant leak (white)So assuming it's oil smoke (blue.)Oil is getting into the cylinders somehow, most commonly via worn valve guides, worn cylinders, worn/broken oil control rings. Can't think of too many other things it can be although if the engine is not "breathing" properly it can pressurize the crankcase and force oil into the cylinders past the rings or valves.
The engine breathes through the hoses from the valve cover to the carbs.
 
That summarizes it! One additional suggestion; I have heard of oil being sucked into the brake vacuum booster and causing smoke, but I would be inclined to suspect the rings may be worn, especially on the cylinder with only 115 psi compression. It willlikely run as is for a while if you cant afford to fix it properly right away, but its tough on air quality, much better to fix it!
Simon.
 
Having just gone thru the "Insect Fogger" TR-6 mod, my culprits were the oil rings. I'd suspect that with low compression on one cylinder, the oil rings could be worn as well. Check the plugs on each cylinder and see if the one with the lowest compression has oil on it. That's what caused my original decision to rebuild my engine, plugs fouling with oil. Good luck!

Mark
1970 TR-6
 
Had a look at the spark plugs, number 5 was wet with oil. So I guess I need too do a ring job. Do you recommend reboring the cylinder's as well. Just seems funny to me that it doesnt smoke when I take it on the highway. Is there any sure way to tell if its rings or a valve problem?

Thanks
 
run a compression test and get a reading for the cylinder. Then put a tablespoon of oil in the spark plug hole and run the test again. If the compression improves 20 or 30 lbs then your rings are shot.
 
The reboring part is dependent on what you find when you take readings of your cylinder walls to see how much wear has occured. When I rebuilt my engine after 150K miles, the cylinder diameters were still within .002 of the factory specs. I went with std rings without reboring and the car runs fine with 148 to 150 compression readings. A good clue to cylinder wear will be the ridge you find at the top of the cylinders when you pull the head off. A thick ridge means more than likely a rebore will be in order. little or no ridge (as mine had) indicates little cylinder wall wear. I'd always measure it to make sure tho. Good luck!

Mark
1970 TR-6
 
/ubbthreads/images/graemlins/iagree.gif and if you don't rebore the cylinders but decide to just replace the rings watch out for that upper ridge. You should hone it off or use a special "stepped" upper compression ring that provides the clearance. Failure to do this will probably bust that top ring the very first stroke of the engine.
 
When I took the head off to do the valve job, the cylinder bores did not have any ridges or any bad scoring, but they did look glazed. Some one told me that I should be able to see honing marks, there isnt any. Could this be part of the problem?

Thanks
 
All above possible, but typically if it smokes on start up and then stops, you're likely to be looking at valve stem seals, which is a fairly easy job to replace. Most of the other culprits will continue smoking all the time.
 
The steps to redo the cylinders if the measurements are OK are to use a ridge reaming tool to remove all of the ridge thats formed at the top of each cylinder, and then a whip hone to remove the glazing on the cylinder walls. Your "glazed" look is just normal wear from the rings. I still think it's oil ring or rings that is your problem.

Mark
1970 TR-6
 
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