• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR4/4A Oil pooling on cylinders

Share this page

T

Tony P

Member
Offline
I need some help with this one. Finished a complete engine rebuild and the engine averages 1quart of oil per drive of about 80 miles. With the smoking I knew that I had to break in the rings. After 800 miles of smokey driving I took the car to a mechanic, he removed the head and oil was puddled on the pistons! He did a complete head rebuild, guides and valves.
I went to Triumphfest in San Rafael Ca. Round trip of 200 miles car smoked all the way there and back. I got mad and a friend and I removed the head with the intent of changing out the piston rings and calling it square. When we removed the head, oil was puddled on the pistons. This much oil can not come through the rings! Oil pressure never goes over 70 lbs.
what can it be? Any ideas?
 
Have you tried disconnecting the PCV system? Take a look, I think you'll find oil in the intake manifold.
 
More info: Assuming the head is good (new rockers, shaft, new valve guides, new valves), is there any way for the oil to come up past the rings and get to the top of the piston? Seems like it has to come from the head?
I don't think he has a PCV valve connected to the head. We did notice the exhaust valve burned through the gasket in two places.

Jerry (for Tony)
 
I don't understand your statement about the exhaust valve burning through the gasket. Do you mean the head gasket was burned through near two of the exhaust valves? A picture might be helpful.

Unless it's an early TR4, the crankcase vent line would normally be connected to either the air filters, or the intake manifold. Either way, oil mist can find it's way through the tube, into the manifold and then to the combustion chambers via the intake valves. Just a possibility to investigate.

Certainly oil can find it's way past the rings and into the combustion chamber (which is on top of the pistons). But if the cylinder were firing, the oil should burn as well and you'd find mostly just the burned remnants (oily black carbon). Since it sounds as though you found liquid oil (?), it must've gotten in there after the engine was shut off, which would seem to indicate it came from above and ran down. Also, it wouldn't be likely to have the same damage in all 4 cylinders. (Did you find roughly the same amount in all four?)

But at some point, especially when there is no obvious explanation, you need to start checking everything it might be. Note that it wouldn't even have to be the rings that have a problem, a broken piston could allow large amounts of oil past as well. This one was sure fogging for mosquitoes!
(And had liquid oil on top when I got it apart.)

 
Exhaust gasket to the exhaust manifold was burned through in two spots. I am betting that was because the manifold was not tight against the head? The pistons are new , but excessive oil from a previous poor valve job probably did not get the rings set. We think the oil looked about the same on all four pistons. The rockers have new shaft and rocker arms and are tight. The oil pressure is 60-70 so the rockers are getting plenty of oil. I wonder if there is just too much up there for the head to drain off to the tappet holes. The valves on this engine do not have valve seals, but we could add some like the o rings put on a Healey 6 cylinder engine. Mechanically, we can't see why it is burning oil at this time???? any other ideas?
 
I have an early model TR4, no PCV valve. I have a breather vent for the sump and the old style valve cover breather cap, both cleaned and reconditioned during the rebuild.

As to the liquid oil on the pistons, yes there seems to be equal amounts on all 4. When I start the car it smokes from the burn off of that oil. At high speeds there is some but not a lot of smoke. At slow speeds the oil seems to build up and when I accelerate it comes out the tailpipe.

I will check the lower breather tube for obstruction and make sure it is clear. With the pressure relief valve set at 70 lbs as indicated by the oil gauge, I can't imagine that there is that much pressure to overload the rocker arm and deliver so much oil that it would be forced into the combustion camber via the valve guides.

Is there any other way that the oil could get into the cylinders other than the guides? When I remover the head I checked the intake and exhaust manifolds for oil moisture and there wasn't any. They were just black from all the soot of the burned off oil.
 
The guides don't need seals but I can't think of anything else that would allow enough oil to enter the cylinders to cause a pool on the pistons (except maybe the wrong size oil rings, which seems very unlikely). How much checking/ replacing of valves and guides was done? Can you confirm that they were reamed properly?

Tom
 
Logically, the oil can only come from two places - from above or below. As TR3 Driver said, its more likely to have come from above through the guides. I agree. One other possibility - the ring grooves were not staggered when the new rings were installed. Remote, but Murphy's Law...
 
pdplot said:
Logically, the oil can only come from two places - from above or below. As TR3 Driver said, its more likely to have come from above through the guides. I agree. One other possibility - the ring grooves were not staggered when the new rings were installed. Remote, but Murphy's Law...
Click to expand...

Yup, I agree entirely with Randall and you, It's coming from the top and there's lots of it. I think you could line up all the ring gaps on the 3 piece oil ring and not get that much oil.
 
Do you have an auxillary oil line running to the rockers? That line is sold as an imrovement coming from an oil gallery to the back of the head. It actually floods the head with too much oil. If you have that line try removing it and see if that stops the problem.
 
No extra oil line to the rockers. Our friend that is a real mechanic says the guides and valves now have real close tolerances, close to 2 thousand. We pulled the pistons and there were signs of too much oil. So Re Hone the cylinders and order new rings.
 
I had a friend that has a mechanic shop (his own business) he redid the head with new valves and guides. Reamed to .002 so they just slid nicely. Re lapped the new valves into the seats. Installed o ring seals like in the Healeys and I am confident that the head is sound and ready to go.

we decided to drop the pan and removed the pistons. They looked fine and cylinder 3,4 looked real good whereas 1,2 could have used more time to seat in. But I said let's put new rings while it is apart. The rings gaps in a couple cylinders were not offset but that could have been caused while handling the on removal.

A recommendation to use hasting rings and oil seal was taken and they are on order for Monday. I am installing new bearings on the pistons for added insurance.

i will post results after startup on Wednesday. Thank you all for the input.
 
Had exactly the same issue with a midget engine recently. Also recent rebuild. Loads of burnt oil and a dime of oil on the top of each piston. Went through all the things you have including rebuilt head and breather system. Problem in the end was that I had fitted the oil control rings incorrectly. The spacer between the two scraper rings had been fitted with an overlap. The should have been set with ends butted. Replaced with the correct set up and no oil burning.
Hope thus helps
 
Well here I am again with some more input. As you all know there was the dilemma of trying to find the reason for the oil pooling on the pistons. This is what happened: after a complete engine rebuild I had the problem of the engine not breaking in and continued smokeing out the tail pipe. I got upset and needed the car for Triumphfest on Oct 2nd.
I pulled the head that had been machined and supposedly reconditioned, but upon taking it to another mechanic it was discovered that the same valves were used and the guides were nurreled to tighten them up. So new valves and guides were installed and I was good to go! So I thought, on the way to Triumphest and back the car smoked the same and I used 2 1/2 quarts of oil in 250 mile, not good.
I waited two days and Jerry and I pulled the head again, more oil pooled on the pistons! I took the head to the mechanic that did the valve job and he rechecked the work and said it was fine and to specs. He then told me the words that make your day seem long "it has to be the bottom end, the ring" I was not happy.
So, Jerry and I pulled the pistons (engine still in the car, messy) and discovered this: the compression ring gaps were to close together in two cylinders and the corrugated oil ring were damaged. If you have installed oil rings, there are two outside solid rings and one corrugated in between them. With these corrugated rings there are small flanges on the ends that must butt together and not overlap or you will get oil pumping (liquid oil on the pistons). Well as I removed the oil rings I discovered that in 3 cylinders one of the flanges that were supposed to butt had broken off and that allowed the ring to collapse inward and course oil pumping in 3 cylinders.
To wrap this up, once I told the mechanic that he was right about the rings he recommended that we replace all the rings with Hasting Rings. The oil seal ring for the Hastings was a 1 piece ring an could be installed up or down, very easy install. All gaps were fine and facing opposit each other. The reinstall went without problem, and the car started up and ran great, no smoke. Hastings recommends that the car be driven to 35 miles per hour and then opened up to 55-60 MPH at full throttle at least 10 times. Once this is done drive the car carefully until the engine finishes the break in.
Well I did that and all is well, so far. Thank you all for the information, and I will keep in touch.

tony
 
Glad you got it sorted out. The one piece oil rings were original equipment and once came with the replacement piston and liner kits. Far superior to the 3 piece, IMO. Tom
 
Hey Tony
Met you at Triumphest. How is the engine running now? Hoping lots of compression and no smoke!

Pat
 
Hey Pat, two things, yes the car is running great! No smoke at all, oil level is right where it was when I went on a run of 210 miles and it is just as clear as when I put it in. Jerry followed me for a ways and he said the exhaust was clear.

second thing I have a lead on a sway bar for a TR4, I am sure it will fit you 250. Let me know if you think it will fit. Ask Jerry for my phone no.
 
Tony does not need much compression, he barely gets it above 2500 rpm. But the car is running well. I never have seen rings that did not set in and pump so much oil into the cylinders. I think the different brand of rings we put in (Hastings) had a lot more spring to them.

Now waiting on parts for a MGB! Should have that fixed on Monday with Tony's help.

Jerry
 
Tony P said:
second thing I have a lead on a sway bar for a TR4, I am sure it will fit you 250. Let me know if you think it will fit. Ask Jerry for my phone no.
Click to expand...

Hey Tony. A TR4 sway bar (TR4 versus TR4A) should not fit a TR250 due to the suspension and frame differences.

Scott
 
Back
Top