Jump to content

TR4A engine oil leak - just purchased


Recommended Posts

Sold my TR3B which never leaked a spot of oil for a travelling oil leak called a TR4A. Big mistake, the seller a TR repair shop lied because assured me it did not leak oil.
I know I have excessive crankcase pressure and oil leaking out of rear crankshaft oil seal and weeping out of dipstick tube and after lots of reading think I know why.
Running stationary in the driveway up to 2000 rpm no leaks but 2500 and more it just pours out.
It has the standard PCV valve but the oil iller cap in unvented and from what I read should be vented, pictures show a cap with a lump on the top.
Dismantled the PCV valve and cannot find anything wrong. Done a vacuum test with gauge between PCV outlet and inlet manifold. Readings fluctuate a small amount, idle 17/19, 1500/2000 rpm 20/21. They look good to me. Now I put the gauge between the rocker cover outlet and the PCV input, reading of zero on tickover and a struggle to get to 0.5 at 2000 rpm. This suggests to me no gas flow, hence pressure build up. But I do not have any air flow into the engine either. Diagrams I have looked at show a pipe from the air cleaner to the rocker cover to admit air. I had a Cobra with a 6.2 Chevy with that pipe on one bank and on the other bank a pipe going to a PCV and out to the inlet manifold. I can understand how that works. Apart from getting rid of the car at a huge loss what is the solution.

Link to post
Share on other sites
22 minutes ago, eng622 said:

Sold my TR3B which never leaked a spot of oil for a travelling oil leak called a TR4A. Big mistake, the seller a TR repair shop lied because assured me it did not leak oil.
I know I have excessive crankcase pressure and oil leaking out of rear crankshaft oil seal and weeping out of dipstick tube and after lots of reading think I know why.
Running stationary in the driveway up to 2000 rpm no leaks but 2500 and more it just pours out.
It has the standard PCV valve but the oil iller cap in unvented and from what I read should be vented, pictures show a cap with a lump on the top.
Dismantled the PCV valve and cannot find anything wrong. Done a vacuum test with gauge between PCV outlet and inlet manifold. Readings fluctuate a small amount, idle 17/19, 1500/2000 rpm 20/21. They look good to me. Now I put the gauge between the rocker cover outlet and the PCV input, reading of zero on tickover and a struggle to get to 0.5 at 2000 rpm. This suggests to me no gas flow, hence pressure build up. But I do not have any air flow into the engine either. Diagrams I have looked at show a pipe from the air cleaner to the rocker cover to admit air. I had a Cobra with a 6.2 Chevy with that pipe on one bank and on the other bank a pipe going to a PCV and out to the inlet manifold. I can understand how that works. Apart from getting rid of the car at a huge loss what is the solution.

It definitely should have a vented cap, and I'd imagine that would help the circulation of air and fumes being drawn into the PCV valve. Have you run the engine with the cap off, and does it make any difference ?

Kevin

Link to post
Share on other sites

Hi Eng622,

                       have you a name and where are you. If in the UK you do have some purchasing rights but not always easy to get sorted.

If the crankcase pressure is due to a worn engine (poor rings etc) then you need to get that sorted before sorting the leaks - big job.

Do a pressure check (wet and dry) for the four bores.

If you believe the engine to be good then start the hunt for the leaks.

You could simply remove the PCV and hang a pipe from the rocker cover down the Dizzy side of the engine. That eliminates the PCV which can go duff.

Clean the engine so no oil exists on the outside (I use Wynns Brake cleaner).

Run the car for 10 miles or so then check for leaks. Repeat this as necessary.

There should be a 'felt' seal on the dip stick.

make sure ALL the sump screws are tight. I have just had to remove/apply sealant/refit all my sump screws as they were leaking around the thread/spring washer.

Check where the mechanical fuel pump attaches. Another leak area.

Rocker cover gasket can leak by the bucket load - usually at the back.

The 4A never usually had a pipe from Rocker to carb filter ( that's the TR4)

 

Start with that lot and report back.

 

Roger

 

Link to post
Share on other sites

Name is Melvyn from Nottingham. The dipstick felt seal was missing, just an O ring so made up a sponge seal. Doing that has put pressure on the petrol pump as oil now leaking there.

I cannot find for sale the correct vented cap. Cannot return the car as purchased without warranty.

The car runs fine good mpg all spark plugs a pale straw colour and no oil on them, unlike 3B which had darker and one oil smeared plug.

There are fumes from the oil filler cap and from the rocker cover pipe and some oil in the PCV but the outlet pipe to the manifold is dry. Done the pinch test on the rocker pipe to PVC and the revs drop a little. Taking this pipe off I feel strong suction putting finger over pipe end. These are the tests I have read about but as said a vacuum test with the gauge T eed to the PVC inlet reads zero, so cannot see how any gases can be sucked into the manifold and hence relieve the pressure build up.

 

 

 

Link to post
Share on other sites
16 hours ago, boxofbits said:

It definitely should have a vented cap, and I'd imagine that would help the circulation of air and fumes being drawn into the PCV valve. Have you run the engine with the cap off, and does it make any difference ?

Kevin

Surely any cap will do if you have ditched the PCV & fitted a proper breather system into a catch tank etc.

Link to post
Share on other sites

Would like to try a vented cap if i could source one. Can try running with cap off first.

Forgot to mention some drips out of the sump plug, never did like tapered threads. The car was serviced by the seller with new oil and filter.

Exhaust smoke is normal grey/white no blue 

Link to post
Share on other sites

Hi Melvyn,

Speaking from experience...  as Roger says - I would quickly try the car without the PCV and just drop a pipe to discharge to ground, clean up the oil around the dip stick, and just run it for 20 or so miles.Then have a look and see if there's still oil coming out past the dip stick. My bad experience originated from me dispensing with the PCV and using a pipe as described, but choosing too small a bore and allowing it to get blocked (as it will). This increase in pressure blew oil past the dipstick and the front oil seal, no problem. Hell of a mess. I'm not saying you might not have other issues, though!

Frank

Link to post
Share on other sites

I have very good experience with the PCV-valve on my TR4A, no mile  without.

It gives a regulated minimum vacuum on the rockercover and engine to get a controlled ventilation.

And to get the fumes burned and not to the environment.

It also is an oil separator, therefore the valve and hoses must be fixed to give the oil a change to flow back to the rocker cover.

I've seen some PCV valves fixed "backwards", that courses the oil running through it's center drill to the carbs.

Then you must not complain about the PCV-valve but about the mechanic.

Link to post
Share on other sites

sounds like you are fighting a loosing battle with oil coming out the fuel pump and dipstick hole...the crankcase pressure is much to high...the PCV system is overwhelmed. The engine is end of life. Get the vendor to rebuild it.

Link to post
Share on other sites

I read somewhere that the PVC regulated vacuum is 3/4 ins if that is correct then mine at zero is inadequate. Cannot see fitting a pipe from the rocker cover outlet to a low point is going to have any effect unless I can get air in through the oil filler cap.

I had a Stag with a 4 barrel carb and there was a pipe from one cam cover going to the base of the air filter. The base used to get quite oily but the fumes went into the carb and manifiold. I guess the engine had wear but I did 11k miles before selling and it never got any worse, did not leak much oil but burnt quite a lot at 250 miles/pint.

Link to post
Share on other sites
17 hours ago, eng622 said:

Cannot see fitting a pipe from the rocker cover outlet to a low point is going to have any effect unless I can get air in through the oil filler cap.

Letting air in isn't going to reduce your crankcase pressure.

Pete

Link to post
Share on other sites
13 hours ago, eng622 said:

OK, so what are the required modifications I can consider that might work long term.

Start by just venting the rocker cover to atmosphere via a piece of hose. Do a compression test, dry and wet.

Pete

Link to post
Share on other sites

OK done a simple test today and removed the oil filler cap. On idle it spits a bit of oil out so did not want to drive like that so put a cloth over the opening then had a short drive came back let it idle for a few minutes , switched off and looked for leaks.

The cloth was quite clean, I  expected it to be quite oily. No oil underneath, no oil weeping from dip stick tube (now sealed with a make shift seal) and no weeping from the petrol pump.

However after 5 minutes a couple of drops from the sump plug and a lesser amount from front of bell housing.

When I took the cap off the idle revs increased a little. I noticed with cap back and pulling the pipe off going to the PVC from the rocker that the revs increased just a touch more.

What does all this convey?

Link to post
Share on other sites

Further update. Been for a 105 mile run today with cloth (several layers) over oil filler cap. Stopped several times to check for leaks. Sometimes just a weep around petrol pump. On return after a few minutes a small amount from bell housing. Could live as is but want to do better.

So going to buy a non vented oil filler cap and experiment (cannot get the vented type) by drilling a hole in centre. What should I try to start with 1/16 inch? If it all falls apart will drill 1/8 and put in a rivet to hold seal/washer. Hole through rivet must be around 1/16.

Can anyone post a picture/description of how the vented type is constructed as thinking could convert the non vented to vented to as near as factory done.

Link to post
Share on other sites

Melvyn - I reckon you will need a much bigger hole than you are suggesting in your cap.

Alternatively,  why don't you go down the same route as a TR4 and do away with the PCV valve altogether and fit a snorkel crankcase breather next to the fuel pump - they are not readily available but do come up for sale occasionally - they fit where there is currently a core plug in the block next to the fuel pump - bit of a fiddle to get out but Roger ( Hogarth) is an acknowledged expert!!

You can also retain your 4A rocker cover and use the vent outlet to vent to a catch tank or stick a long rubber hose on it and stick it through a conveneint hole in your chassis - good anti rust method!

Cheers

Rich

Link to post
Share on other sites

Melvyn. This is a crank case vent pipe that Rich suggests. 

Rather than mess with an oil cap. A vented rocker cover should help. This is the way the 4,s went when the crank case vent was stopped. 

So a min 8-10mm hole ?

on my 3a I have both the rocker cover and crank case vented to a breather oil catch tank. 

Triumph TR2/3/4 Breather Pipe https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F232994681691

 

H

Link to post
Share on other sites
1 hour ago, Hamish said:

Blimey he knows how to charge!

Stuart.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.