TR4/4A Oil oil everywhere

[Foura]

We recently went on the annual Triumph National Rally in the Clare Valley, a major wine district here in Australia. A couple of months before, I took the car to a Triumph specialist to fix an oil leak that he had diagnosed as coming from the pushrod tubes in the head. He removed the head and sealed the tubes. He also noticed that 2 of the lifters and the cam were worn so he had the cam reground to a slightly hotter profile (280 degree duration).

We set off on our trip and on the second day we noticed a LARGE amount of oil under the car. It seemed to be coming out of the dipstick hole. We put a couple of litres in and continued on to meet up with the rest of the group we were travelling with. After a group consultation that evening - six guys with beers- I blocked off the (new) PCV valve and ran a piece of heater hose straight off the rocker cover breather to fresh air. That seemed to reduce but not eliminate the problem.

We completed the trip and the car appeared to run well. However, we used 6 litres of oil in 3000km. Yesterday, I re-connected the PCV valve and took the car for a run. I parked it over some newspaper when I got back and it dropped a large amount of oil, again mainly from the dipstick. It has suction through the PCV valve but it has quite a strong draft coming out of the oil filler cap if you take it off when the car is running. Apparently the compression in all 4 cylinders is good.

They took pity on me at the Rally and awarded me a prize of 5 litres of Penrite but that is not a long term solution. The collective wisdom of the forum would be greatly appreciated.

 

[TR3driver]

It sure sounds like excessive blowby, like maybe a broken piston ring or scored cylinder wall. Who did the compression check? Regardless, I think I would follow up with a leak-down test.

Also, is the felt washer in place on the dipstick? I doubt that is the problem, at least not all of it, but it should be there.

 

[TomMull]

I agree with Randall on the leak down test. Excessive crankcase pressure may also have contributed to the leak from the pushrod tubes. I would also however make sure that the pcv system is working. Venting the valve cover directly to the air may not evacuate the crankcase as well as venting into the vacuum of the intake.
Tom

 

[KVH]

It sure sounds like excessive blowby, like maybe a broken piston ring or scored cylinder wall. Who did the compression check? Regardless, I think I would follow up with a leak-down test.

Also, is the felt washer in place on the dipstick? I doubt that is the problem, at least not all of it, but it should be there.

Having just rebuilt an engine, and still trying to resolve my oil issues, what is this about a scored cylinder wall, and how would that happen? So, the idea either way, rings or not, is that compression from the head leaks into the crankcase, right? I assume that would also result in more rear main seal leaking, too?

 

[TR3driver]

There are various ways it can happen. I was chatting with a fellow just the other day that had had the wrist (gudgeon) pin clips come loose and the end of the pin gouged the cylinder wall. In fact, that's what made me think of it now, as we were discussing why his car was blowing so much oil. ISTR one of Kas Kastner's Triumph competition books recommended replacing the clips with plastic "buttons" just so they can't come loose.

Broken rings, (perhaps from a ring gap not big enough) or any sort of foreign object sucked in through the intake.

Sometimes, even a severe bout of overheating can cause it (tho I've not heard of that in a TRactor motor).

And of course, any damage to the piston can be reflected in the cylinder wall.

Anyway, yes, the idea is that the combustion gases leak past the rings and blow out through the crankcase. Particularly on engines with the 4A PCV setup, the result can blow oil out almost anywhere, including the rear main seal, rocker cover, and dipstick.

The 4A PCV system suffers a particular limitation, because it relies on manifold vacuum to pull the crankcase fumes through the PCV valve. But with the throttle wide open, when blowby is at it's worst, there is practically no manifold vacuum! And on the 4A, there is nowhere else for the fumes to go. So the crankcase gets pressurized until the pressure is enough to push through the relatively small orifice in the PCV valve.

On American engines, there is an alternate flow path provided to cover that case, through a relatively large diameter tube connected to the air intake (similar to the later TR4 setup). But somehow, Triumph didn't get the memo.

Even that wasn't a complete solution, of course. I used to own an Oldsmobile that would blow a quart of oil out that tube in just 20 or 30 miles if you kept your foot on the floor. Had to disconnect it from the air intake, so the oil wouldn't foul the filter. But MAN what a ride! Made an E-ticket seem tame.

 

[TuffTR250]

Is it possible to install a breather pipe on the TR4A? i.e. on the lower left hand side of the engine. My TR3 that has a TR4 engine did not have the breather pipe when I got it. Nor did it have any kind of PVC system. It was blowing a gale out the valve cover breather and a lot of oil was accumulating all over the valve cover. So I knocked out the plug for the breather pipe and installed a pipe a club member gave me. I no longer have air nor oil blowing out of the valve cover breather. I do get some oil dripping from the bottom of the breather pipe but not a lot.
Regards, Bob

 

[TR3driver]

Should be the same process. AFAIK they never removed that port from the block casting, just put a plug in it like your TR4.

 

[malbaby]

Hi Barrie.....As suggested above, do a compression and leak down test initially.
Let us all know your findings.

 

[Foura]

Thank you for all the suggestions. I hope that we did not leave too much oil on your driveway, Malcolm! Great car by the way.

My understanding is that the oil in the rocker cover drains through the pushrod tubes and back to the sump. Last night, I tried blowing through the pipe on the rocker cover that connects to the PCV valve. I could not get air to go either way, in or out. The pipe is completely clear. So how does the oil get back to the sump? And how does the pressure that I can feel when the engine is running and I take the oil filler cap off get from the sump to the rocker cover?

The mechanic is suggesting that I may have a broken ring which is letting pressure into the sump. The car is not blowing any oil but he puts that down to the oil rings being OK. He did not see any evidence of scoring on the bores who he had the head off. He is also wondering whether excessive back pressure from the muffler could be causing the problem. I went from a dual muffler TR4A system to a single 3 pass muffler a while ago and that may have coincided with the increase in oil leaks. And it is now much worse with the new cam which has greater overlap. He suggests that a straight through muffler might help with the leak and also release a few more HP.

I will retrieve my compression gauge and do a test and see what the results reveal. The annoying thing is that the car is otherwise running very well.

 

[Merlin63Tr4]

Sounds like like your rocker cover PCV nipple is clogged/blocked, you should be able to blow thru it easily.
If you remove the rocker cover and flip it over you will see a spot welded oil baffle over the opening for the PCV nipple. This baffle is there to allow only oil vapors to pass thru and to stop oil droplets from passing thru the PCV system.
This baffle is open to the inside of the rocker cover at both ends to allow the PVC system to breathe.
Check to see if the openings are free and not clogged with burned oil or sludge, and also check to see if someone in the past has hammered the baffle flat against the inside surface of the rocker cover and thus blocked the PCV nipple.

M.

 

[TR3driver]

The pushrod tubes are how the oil gets back to the crankcase, and how the blowby comes up from the crankcase. But the crankcase is sealed (except for the leaks), so you aren't able to blow air through it.

A broken ring (or more than one) is a definite possibility (as I mentioned above).

Exhaust back pressure seems very unlikely to me. Have to be a lot of pressure, and some very worn exhaust valve guides.

 

[gbtr6]

+1 on the broken ring, and or lands in your piston. Mine was blowing oil out, and compression in #1 was poor. Did a rebuild and that piston was broken. Yours may not be that bad.

Perry

It sure sounds like excessive blowby, like maybe a broken piston ring or scored cylinder wall. Who did the compression check? Regardless, I think I would follow up with a leak-down test.

Also, is the felt washer in place on the dipstick? I doubt that is the problem, at least not all of it, but it should be there.

 

[Foura]

Sounds like like your rocker cover PCV nipple is clogged/blocked, you should be able to blow thru it easily.
If you remove the rocker cover and flip it over you will see a spot welded oil baffle over the opening for the PCV nipple. This baffle is there to allow only oil vapors to pass thru and to stop oil droplets from passing thru the PCV system.
This baffle is open to the inside of the rocker cover at both ends to allow the PVC system to breathe.
Check to see if the openings are free and not clogged with burned oil or sludge, and also check to see if someone in the past has hammered the baffle flat against the inside surface of the rocker cover and thus blocked the PCV nipple.

M.

I have an alloy rocker cover which does not have the baffle. The pipe is about 1/2" in diameter and completely clear. Thanks for the suggestion. I have now retrieved the compression gauge and will give it a go and report back.

 

[Foura]

We finally got around to the compression test this weekend. We took the car to the hardware store to buy bird netting. Got it nice and warm and then took the plugs out when we got home. The readings were 170 for all four cylinders. There was a slightly faster leak down on number 4. 170 seems reasonable for a 2188cc motor in good condition, but it is still pumping oil out of the dipstick in large quantities.

The only other possibility is that I have a TR6 pedal box and brake booster. I am wondering if I have a leak there that is reducing the vacuum in the manifold and thus reducing the vacuum through the PCV valve.

Further reports later!

 

[malbaby]

Barrie....would I be correct in assuming that you have test run the engine with the rubber hose from the rocker cover to the PCV valve disconnected from the rocker cover..... [possibility that there is an air blockage in the PCV valve line].

 

[TomMull]

OK, perhaps the blow-by cause is at least unlikely bad rings. To go back to the beginning, it would seem that the large leaks from the dipstick tube started after the new cam and pushrod tubes. Seems like the leak and the work might be related. Have you questioned the "Triumph specialist" who did the work? Do you have a detailed repair order of everything that was done? For one, confirm the quantity of sump oil without relying on the stick itself (can't remember if that was done).
Tom

 

[Foura]

I originally thought that the oil leak was from the gearbox because there was a sticky residue on the back of the car. I took the gearbox out and took it to Geoff because he had rebuilt the box 18 years ago. He checked it out and said that it had a minor leak around the selectors but it was not the source of the leak. He came and had a look at the car and said that it appeared to be coming from the pushrod tubes. So I had the car towed to his workshop. He has a very steep drive. He rang me after he started work on the car to tell me that he had taken about 15 litres of petrol and oil out of the sump. I assume that the valve in the mechanical fuel pump had failed and allowed fuel to drain through the engine into the sump in his driveway. He took the head off, sealed the pushrod tubes, replaced the fuel pump and had the worn cam reground, as well as replacing two lifters and the PCV valve. I originally had a T-piece in the hose from the PCV to the manifold which I ran to the brake booster. He tapped a seperate fitting into the balance tube to run to the booster.

I have checked that there is vacuum going through the PCV valve so no blockage there. I agree that the leak is far worse since the work was done. The challenge is to identify which part of the work is the problem. One possibility is that the petrol leak has diluted the oil and glazed the bores, but if it had 15 litres in the sump, it would have been pumping a geyser out of the dipstick! I believe that only happened in his steep driveway.

 

[malbaby]

Have you tried removing the oil fill cap in the rocker cover and with the engine check to see how much or how little air pressure there is.

 

[TomMull]

15 liters is a lot of oil/fuel and it is certainly possible for internal damage if more than half that was gasoline but I wouldn't necessarily jump to that conclusion. You are still showing decent compression. Perhaps you've done this but I would first absolutely confirm that the oil is no longer being diluted. You can do that by draining and measuring the drained volume, by using your nose, or by oil analysis and/or viscosity test.
Then refill with the proper quantity of fresh oil, mark the dipstick and re-check.
In my experience, even if you do have some blow by, something else seems amiss.
Tom

 

[mctriumph]

Your car can handle only some blow-by from the rings due to the primitive crankcase
ventilation it has. Likely at speed it is forced out the rear main scroll and even the dipstick tube.
Old Tr's often get a fresh set of rings thrown in on worn out pistols/sleeves.The new rings dont last long
and this is where I think you are,broken ring pergatory...
MD