Rocker & Crankshaft Case Breathing

[Cotswoldiver]

As a quick bit of background, my 4A returned from the States in the early '90 and came into my ownership last summer - my original quest was to sort out the rear crankshaft seal but here we are 10 months later and a whole bundle of other issues have been solved including a rebuilt engine and at no surprise is now way over my original budget and contingency without even having the joy driving the car properly yet.

I've tried to read all the back posts on the PCV set up and have been wondering/concluding that if over the years the PCV set up together with a plug in the crankshaft case contributed to the engine pressure issue anyway?

So to the question, the PCV set up has not been replaced, I am considering the Raceorations engine breather kit - I hear what is said about Revington's alloy box v Raceorations fibreglass catch tank, but at £250 delivered (much more for Revingtons) plus the labour costs involved at the moment its about trying to save even just a few pennies as unfortunately the engine is back in situ and the crankcase core plug still needs to be removed - and yes, even to this I confess hindsight is a truly wonderful gift.

Am I - 

a) asking for trouble if for example only a gauze style breather was fitted to the rocker cover and the crankshaft core plug is left in ( The oil filler cap is just a simple version with a pin hole which previously did unsurprisingly weep)

b) as for A) but remove the core plug and add a simple downward facing breather tube with a fire trap in the crankcase

or as I really suspect having invested so much time & selling of kidneys and other body parts on ebay to fund this

c) continue to bite the bullet and fit the Raceorations kit?

 

I've run out of kidneys, still trying to get back off the floor from seeing the latest workshop labour bill so some calming, sensible reasoning from forum members would be most welcome whilst I make another mug of tea from the same teabag as last time and await the response ...

Be kind, David

[stuart]

You could just do what a lot have done and that is just run a pipe from the rocker cover breather round the back of the engine and down to the bottom of the chassis with the open end facing rearwards to give you some sort of venturi action.

Or fit the PCV and live with it making sure you clean it out regularly

Or fit the Racetorations kit which is what I have and am very pleased with though until just lately it was only plumbed to the rocker cover but on the last engine rebuild I have also removed the block plug and its now plumbed both ways. The Revingtons one Im not keen on as with its perforated top I suspect you would get oil fumes pervading underbonnet whereas the Racetorations one is a closed box.

For the same reason just a gauge type filter on the rocker cover will leave the oil fumes floating round underbonnet too

FWIW its very difficult to remove that plug when the engine is in the car.

Stuart.

Edited September 13, 2022 by stuart

[stillp]

There are many TRs running with just a vented rocker cover. Mine doesn't have a PCV or a breather tube in the crankcase, and yes, it does breathe a little but not enough to worry about.

Pete

[peejay4A]

+1 for the Racetorations kit. Straightforward to fit once you have the crankcase plug removed. 

[ctc77965o]

+1 for original PCV

33 years and 100K+ miles with only a small amount of oil marking it's patch

My advice: spend money on tyres, brakes & suspension

[monty]

I installed the Racetorations kit a few years ago & it has appeared to have worked well. I was lucky that the restorer/previous owner had already fitted an electric fuel pump so the mechanical pump location on the block was easily used for the Racetorations crankcase outlet. The amazing thing to see is the muck/gunge that is deposited in the Racetorations catch tank! A proportion of this muck & gunge would presumably have been sent through the inlet manifold via the PCV. I am sure the engine breathes & runs better & certain that it has got to be better putting that muck into a catch tank.

[Andy Moltu]

Things to bear in mind:

Try and get the pipes to go uphill to the tank to give the oil mist chance to condense and run back into the rocker and or the block breather and to mount.

The picture doesn't show well that there are 2 breathers one from the rocker cover to the top of the tank and the other from a breather to the plate that blanks the fuel pump (if you run an electric pump) to the bottom of the catch tank.

The larger pipe exiting the top of the breather goes to the atmosphere in the airflow beneath the car.

As it has an after market rocker cover with no plate over the breather outlet, any oil that condenses in the catch tank drains back in though the lower breather when you switch off.

[TR4Tony VC]

This is why I designed this billet cover to allow breathing on both sides, so that you can breathe to the manifold or a tank, or both. Just swat an AN10 outlet or blanking plug in / out which gives you a 1/2 inch internal diameter hose into your tank.

Using a breather tank certainly gets rid of any top end pressure and helps stop seals and gaskets blowing oil out, but you also see and smell early evidence of a problem with rings etc. from the top of the tank, so that’s a winner.

A block breather on the 4 cyl wet liner engine makes sense for a number of similar reasons and an easy solution is to use the fuel pump outlet to locate a breather, but I means using an electric pump. With the quality issues with the current AC type replicas, this might be less trouble option.

I don’t like draughting to the road and you certainly can’t go on a track, rally or hillclimb, so a sealed in system is what I use.

regards

Tony 

[Cotswoldiver]

Thanks to everyone for their help on this. The different view points/insights have been really helpful. Loving the design of Tony's billet cover, so much thought and a terrific outcome in my opinion. Taking a closer look at the core plug next week, it is looking possible so fingers crossed

Many, many thanks

David

[Z320]

12 from 10 point to the PCV valve!

The most problem with this valve are car owners not understanding what its for and how it works.

Otherwise it can’t be explained why most of them are removed with „strange“ arguments. Or if still fitted, most of they are fitted wrong.

In short words:

it is a vacuum reducer valve, it sucks the gases out of the engine with a gentle low pressure.

It is also an oil separator, therefore it must be installed horizontal of slightly forward to allow the oil to flow back to the rocker cover.

Ciao, Marco 

[Z320]

Thus is from a club mate‘s TR4A

„I know how it works and it is installed absolutely correct“

[qkingston]

I've been following this thread with interest. I have HS6 carbs (ex TR7 - rebuilt by Andrew Turner to TR4a spec), which have the TR7 breather stub on the carb body. I have used this set-up as shown with a hose from the rocker cover, on the grounds that if it worked for TR7 (and the saloons I think?), it should work ok on the 4a. I have since acquired an original vgc PCV which I have considered fitting, question is which would be the better option? I have noted over a number of forum discussions that often as not it seems the Triumph engineers had thought these issues through and come up with a decent solution, which might point to the PCV???

Rgds

David

[stuart]

16 minutes ago, qkingston said:

I've been following this thread with interest. I have HS6 carbs (ex TR7 - rebuilt by Andrew Turner to TR4a spec), which have the TR7 breather stub on the carb body. I have used this set-up as shown with a hose from the rocker cover, on the grounds that if it worked for TR7 (and the saloons I think?), it should work ok on the 4a. I have since acquired an original vgc PCV which I have considered fitting, question is which would be the better option? I have noted over a number of forum discussions that often as not it seems the Triumph engineers had thought these issues through and come up with a decent solution, which might point to the PCV???

Rgds

David

Unfortunately with that Triumph tune rocker cover theres no baffle behind it so even with that small filter in the line you would be ingesting some oil mist.

Stuart.

[qkingston]

OK good point thanks Stuart, so is the PCV a better option?

David

[monty]

4 minutes ago, stuart said:

Unfortunately with that Triumph tune rocker cover theres no baffle behind it so even with that small filter in the line you would be ingesting some oil mist.

Stuart.

Think that is a flame trap Stuart rather than a filter. I have the same trap fitted to my Racetorations setup. I cannot really see that it can be efficient putting ‘stuff’ from under the rocker box back into the carbs or inlet, hence like you I have the Racetorations catch tank kit!

[Z320]

1 hour ago, monty said:

Think that is a flame trap Stuart rather than a filter. I have the same trap fitted to my Racetorations setup. I cannot really see that it can be efficient putting ‘stuff’ from under the rocker box back into the carbs or inlet, hence like you I have the Racetorations catch tank kit!

What does your modern car do with the ‚stuff‘?

[qkingston]

1 hour ago, monty said:

Think that is a flame trap Stuart rather than a filter. I have the same trap fitted to my Racetorations setup. I cannot really see that it can be efficient putting ‘stuff’ from under the rocker box back into the carbs or inlet, hence like you I have the Racetorations catch tank kit!

It is indeed. I see that many of the later Triumph models (Spit/GT6/Saloon) seem to employ this method as per my pic, is it not efficient? Any reason it wouldn't work on a 4a?

David

[stuart]

41 minutes ago, Z320 said:

What does your modern car do with the ‚stuff‘?

Moderns are far more complicated and recirculate everything including some exhaust gases so a bit difficult to compare.

Stuart.

[monty]

1 hour ago, qkingston said:

It is indeed. I see that many of the later Triumph models (Spit/GT6/Saloon) seem to employ this method as per my pic, is it not efficient? Any reason it wouldn't work on a 4a?

David

I am sure it works but in my view I think it is better to recirculate through a catch tank as previously described rather than through the carbs or inlet. You should see the inside of the catch tank! Mainly residue from the crankcase breather probably but some must come from the rocker area.

[qkingston]

Ok thanks Monty, fair point

David

[Z320]

I checked te hose from the valve to the inlet manifold several times the last years, I save my time to do it again.

It was always clean, dry and absolutely free from oil, also the inlet manifold is free from oil and dust (washed clean from the petrol, of cause)