TR4A engine oil usage

[BarryG]

As an update on my previous post I have temporarily ditched the PCV valve. Instead I am now running a rubber hose from the rocker box cover to a rather tasteful oil catch tank (4 pint milk bottle cable tied alongside the radiator ;-) ). Early days yet but the engine is running much smoother and my oil loss is a lot less.

 

There is never any oil in my drip tray in the garage so I guess I must be loosing the oil whilst driving. As I have noted before my plugs are a good colour and no puffs of smoke out the back.

 

Brings me to think could it be the rear crankcase seal? I think I have read in this forum that the seal may leak when stationary and should 'seal' itself when under pressure. Could someone with more knowledge than me confirm if this is correct?

 

Begining to wonder if my oil pressure was too high would oil blow from the back seal. Currently from very cold the pressure can reach 95psi but settles at 70/75 when hot.

 

Would the best course of attack be to install the lower crankcase breather? Again I have read that the lower crankcase generates much more pressure than the rocker cover so would make more sense to vent this area.

 

Sorry its a bit long.

 

Barry

[RogerH]

As an update on my previous post I have temporarily ditched the PCV valve. Instead I am now running a rubber hose from the rocker box cover to a rather tasteful oil catch tank (4 pint milk bottle cable tied alongside the radiator ;-) ). Early days yet but the engine is running much smoother and my oil loss is a lot less.

 

There is never any oil in my drip tray in the garage so I guess I must be loosing the oil whilst driving. As I have noted before my plugs are a good colour and no puffs of smoke out the back.

 

Brings me to think could it be the rear crankcase seal? I think I have read in this forum that the seal may leak when stationary and should 'seal' itself when under pressure. Could someone with more knowledge than me confirm if this is correct?

The scroll seal has limited dealing capacity when stationary. When rotating it works very well - assuming it is not worn out.

 

Beginning to wonder if my oil pressure was too high would oil blow from the back seal. Currently from very cold the pressure can reach 95psi but settles at 70/75 when hot.

The pressure of the oil should reduce to very low once out of the bearing areas. So that shouldn't in itself force oil out the back.

However a high pressure would increase flow and the area around the oil seal may be getting flooded.

Bring the pressure back to 70psi when cold at tickover. When hot at 2000+rpm the pressure should stay around there (ish)

 

Would the best course of attack be to install the lower crankcase breather? Again I have read that the lower crankcase generates much more pressure than the rocker cover so would make more sense to vent this area.

The crankcase and rocker area should be apprx the same pressure - they are linked by the push rod chest.

Fitting the TR4 vent pipe would help reduce excess pressure but you may lose oil out that way.

 

 

Roger

[Geko]

 

Would the best course of attack be to install the lower crankcase breather? Again I have read that the lower crankcase generates much more pressure than the rocker cover so would make more sense to vent this area.

 

Sorry its a bit long.

 

Barry

 

Fitting the original early TR4 "snorkel" vent is the most original set up but it's a swine of a job to fit with the engine in the car, especially removing the plug on the block. The alternative is to remove the mechanical fuel pump and fit an electric pump; and fix a breather pipe on a blanking pate as per the attached picture. The blanking plate is available from the usual suppliers. I have since then removed the filter are replaced it with a reversed U-shaped rubber hose

[BarryG]

Thanks for the info Roger and Geko.

 

I think I will reduce my oil pressure slightly and see what effect that has.

 

When I got the car it came with an electric fuel pump which at the time caused all sorts of problems as a result I have reverted to a manual fuel pump.

 

Geko why did you ditch the filter and resort to the inverted pipe? Did the filter become clogged? And more importantly what was the difference in oil useage?

 

I will report back with the results.

 

Barry

[Geko]

Geko why did you ditch the filter and resort to the inverted pipe? Did the filter become clogged? And more importantly what was the difference in oil useage?

 

 

No but the blow-by fumes spread all over the engine bay which was coated with condensed oil, not to mention the smell in the cockpit. Oil usage was decent, say 1L/ 700 miles, but the main source of leakage was the sump which I found later to be the front middle bolt being too long and having cracked the aluminum front sealing block. It took me a rebuild to find out though,...

 

BTW: https://www.ebay.com/itm/Triumph-TR4-TR3-Original-Engine-Block-Vent-Tube-road-draft-Tube/232524999065?hash=item362391e999:g:WJcAAOSw47dZ3UpC

Edited November 2, 2017 by Geko

[BarryG]

Geko

 

Do you have the end of the pipe below the chassis rail as I have heard that by doing so causes a vacuum as the wind passes over the end of the pipe.

 

Thanks for the link to the Ebay page, unfortunately free local pick up may make it a bit expensive coming from the UK ;-)

 

Barry

[Geko]

it is flush with the top part of the sump. I think the vacuum is called the "Jabbeke effect" (which is a village in Belgium), there must be some articles about it on the forum

[PYU940F]

"Begining to wonder if my oil pressure was too high would oil blow from the back seal. Currently from very cold the pressure can reach 95psi but settles at 70/75 when hot."

 

I think this is a bit high. I was always told to adjust it to 65-70 psi at @ 2000 rpm when oil hot. I try not to exceed 2000 rpm until the engine has warmed so don't really know what a high rpm cold reading would be. Under normal driving 65-70 is what I achieve with about 30 ish at idle. When I had fun at the Blyden track day and I guess the oil got really hot I think the pressure dropped to about 55 at 2,000 but back up to 70 psi at 3,000. I do not have an oil cooler so I guess this is why people fit them. I have always used Halfords classic 20/50 and can see no reason to change.

[Motorsport Mickey]

Flow...flow...flow

 

Is what counts on these older engines, oil ways the size of Victorian sewers ! As long as no inherent faults they run quite happily at 50 lbs, and then you stand a chance of not overwhelming the rear crank scroll.

If you reduce the oil pressure to more reasonable amounts than 90 lbs it should be loads better.

 

Mick Richards

[RogerH]

I say Mick, what's all this Victorian Sewer malarkey.

 

Don't you know we are the TRR - the price of TR5's makes us nearly posh.

 

Roger

[Z320]

Hi Roger,

 

sorry, I did not read all above, here is my experience with the PCV-valve.

 

My TR4A came without one, from the rockerbox only a hose went down under the engine.

So I had to buy a PCV-valve as a repro, I have never seen a open original one.

Oil consumation was always more than 1 liter on 600 miles/1.000 km,

I guess 1,5 Liter - to much to determine it exactly.

 

Last year I realised something must me wrong with my PCV-valve

because I was able to discripe parts others have never seen!

 

The inner "crown" was not fixed and I found that the think down under it is a non-return valve.

That´s the flametrap to avoid backfire from the carbs to the inner engine (with all the gas from petrol and oil).

I guess normaly nobody can see that, I fixed and sealed it, lucky to own a lathe.

 

3 photos deleted because of not enough database

 

Next I realised that it is a vacuum valve to get a active ventilaton on the engine,

but it is also a vacuum regulator to regulate and limit the vacuum on approx. 4 cm water column

(with a vacuum higher vacuum of for example 50 cm water column it would be difficult

to open the oil filler cap while the engine is ideling).

 

3 photos deleted because of not enough database

 

Next I realised the PCV is a also oil separator - but a faulty construction.

There is always oil in it and it must be fixed horizontal or "forward" to get the oil running

back to the rocker box.

 

But the center bore was flat to the ground - but should be walled not to get the oil to the carbs.

Back on the lathe I made some space for a smal "ring" between the "crown" and the spring.

The ring I pressed on the "crown" and sealed it with special clue.

Now less oil runs back to the carbs but still comes some from the (tapered) regulator pin.

 

3 photos deleted because of not enough database

 

Here you see a PCV-valve from VW from the 2000, still in use on these cars.

 

1 photo deleted because of not enough database

 

At all I was able to trop the oil consumation of my TR4A with this

in average from 1,0 - 1,5 liters down to 0,5 liters on 1.000 km.

 

Believe it or not

Ciao Marco

Edited May 23, 2020 by Z320
photos deleted because of not enough database

[ChrisR-4A]

Hi Marco, the problem with the PCV valve is it was added to the TR4A to correct a problem that today does not exist, ie: emissions in certain markets. The TR4 had the best solution with everything venting to atmosphere. There can be only one reason to fit a PCV valve on a 4A and that would be to maintain originality, at the expense of simplicity and reliability.

Regards Chris

[Z320]

Hi Chris,

I appreciate the secondary effekt of a light vacuum

on the rocker box cover and crankcase in any case of engine running

to reduce the direct leak of oil.

Ciao Marco

[monty]

Hi Marco, the problem with the PCV valve is it was added to the TR4A to correct a problem that today does not exist, ie: emissions in certain markets. The TR4 had the best solution with everything venting to atmosphere. There can be only one reason to fit a PCV valve on a 4A and that would be to maintain originality, at the expense of simplicity and reliability.

Regards Chris

Absolutely spot on Chris. I could never understand how a design that throws oil & muck back into the inlet tract via the inlet manifold could be a successful & efficient system. That is why on my 4A I ditched the PCV & run a hose from the rocker cover, along with one from the crankcase, to a catch tank that vents to atmosphere. The gunge in the catch tank proves everything in my view.

Cheers.

[Z320]

My modification on the PCV valve was 2 years ago in Feb. 2016.

Today I had the first examination of the hose that goes from the PCV valve to the inlet manifold and its nipple:

dry, completely dry, no oil at all, not a mist.

That makes me very pleased.

Edited November 11, 2017 by Z320

[RogerH]

I posted this in a new thread in the Technical forum because I couldn't find this thread !!!

 

Hi Folks,

I can't find my original post regarding oil useage in a good 4A engine. - Found it .

There is another thread running on the TR3 forum that gives some info.

Over the last two months or so I have been monitoring the oil consumption on my 4A.

So far with varied driving it is running at aprx 400 miles / Ltr - not very good I hear you say.

Today I removed the PCV (I called it a pressure control valve, but could it be a Pollution control valve) as I have no external leaks

and so believe things are happening inside the engine.

Every now and then I will get a black plug from a pair with the other one running at the correct colour - I don't understand this.

I have noticed in the past with the PCV fitted that if I remove the oil filler cap at tick over the RPM changes significantly.

With the plain pipe fitted there is no variation at tick over. I have also noticed that there is virtually no airflow coming out of the pipe.

I shall now run the engine for a couple of months and see what happens.

I know that Z320 (Marco) has modified his PCV. This may be a sensible approach.

Roger

Edited November 24, 2017 by RogerH

[Paul J]

Hi Roger

I had a very similar problem my oil consumption was what I considered excessive maybe a litre over 400 miles, I did have a little leakage from front sump bolts and coil bolts. I removed my PCV and fitted a K&N type filter to the rocker cover, removed the core plug down by the fuel pump and fitted an outlet to a small catch tank which vents to atmosphere.

This was a trial really but the first thing I noticed was a far better idle.

The oil consumption has reduced to very little, unfortunately at the same time I changed the oil from Halfords Classic to VR1 Valvoline so I'm not 100% sure which modification has changed things though pretty confident it's the breathing system. Ive also stopped most of the leakage wth the exception of the rear seal.

 

All filters have remained dry with no oil misting which surprised me.

Paul

[RogerH]

Hi Paul,

that is very interesting.

I can't imagine that the oil type would stop oil useage - it may help but not significantly (tin hat on for the flak)

 

What filter did you attach to the rocker cover?

Regarding the old breather pipe position (down by the fuel pump) what did you put in its place.

 

Roger

[BarryG]

This is getting very interesting.

 

Unfortunately I have not done excessive mileage since getting rid of the PCV valve and running a rubber hose from the rocker box to

a temporary catch tank.

 

However I have noticed for definate the following:-

 

1. As Paul has noticed the engine is much better at idle, the engine comfortably idles at between 600 & 700 rpm.

2. There is no oil spray along the top of the rocker box by the filler cap.

3. My garage drip tray only has a few drops of oil, so most of the loss must be when driving.

4. Whilst my plugs are not the ideal colour they are much better than previous.

 

Whilst my PCV valve had a new diaghram, spring and metal mushroom (for want of a better description). From what I have read in this thread is

that there appears to be a secondary valve beneath the top one. I strongly suspect in my case that this 'lower valve' is the culprit, I also wonder

what relationship the two valves have with each other. Could it be that a faulty PCV valve interferes with the mixture settings? this could substantiate the smooth idling

 

In readiness I have acquired via Fleabay the proper TR4 vent pipe, which if my oil consumption has not improved after

the above mods I will be fitting.

 

A few days ago I did a Google Image search for 1960 cars showing an exploded view or a photo of the engine out of the car. I was suprised to see

that practically all the egines I found had a Crankcase breather so other than meeting US regulations why was the breather dropped in favour of the PCV valve.

 

Barry

[RogerH]

Hi Barry,

thanks for that.

My engine does not leak externally (amazing). So that is why I have focused on the PCV.

I will take the 4A out for a decent drive tomorrow and fiddle with the mixture to get it right (again )

 

The TR4 breather pipe is worth investigating.

 

Roger

 

PS - just put in a bid for a pipe on the Bay

Edited November 24, 2017 by RogerH

[Z320]

Hi Roger,

 

the crankcase has to be ventilated and the PCV valve is to garantee that by a minimum vacuum.

It's part of every modern car.

 

The false air (? correct word?) from the valve is automaticly part of the carburetor adjustment.

When you open the oil filler cap the valve opens to hold the vacuum and the mixture gets weak.

If your adjustment is correct the ideling rev. will rise.

Put the oil filler cap back and everything is OK.

 

If you want send me your PCV valve and I do the modifikation for you.

 

Ciao &:-) Marco

[RogerH]

Hi Marco,

many thanks for the explanation of the PCV operation.

 

Let me see what I can find before I send you the PCV, engine, gearbox and diff. (perhaps not the engine, gearbox and diff)

 

 

Roger

[stillp]

 

My engine does not leak externally (amazing).

Are you sure it's a TR?

 

Pete

[RogerH]

Hi Pete,

of course I'm certain it is a TR engine

I'm also certain that Santa will be here in a months time.

 

Roger

[BarryG]

Fascinating reading, including when they should be replaced by. ;-)

 

http://www.aa1car.com/library/pcv.htm

 

Barry