Morris Minor Owners Club

Hello all

As some of you may know, I have replaced my engine a short while ago.
For safety reasons I have fitted an oil gauge.
Which made me worry.

Cold pressure is 75 psi, no problem there.

As soon as the oil is on temperature:
at idle: 8-11 psi
anything over 3000 rpm: 40psi

Never over 40, even when I did 70mph.

And yes there is a bit of rumbling, but not an enormous oil consumption (yet) engine is also lacking power.

Do I need yet another engine?
Onne

Keep the oil topped up and keep your right foot light and keep below 70mph (say cruise at 60) and the engine will keep going for a long time.

Use 20W 50 oil - and don't hammer it - should last a good while. Meantime - eyes open for yet another unit. There was one recently on ebay - no bids at 99p start price!! What about your old engine - was the crank ok in it ?

It had pretty bad end float, certainly visible/feelable. No time to rebuild it, just wanted a runner in there again...

Onne, you could try renewing or at least inspecting the big ends. You can
drop the sump with the engine in the car and removing one big end will give
you a good idea as to the worth of fitting new shells. If you can feel a proud
ridge around the crankshaft bearing surface in line with the oil hole then do
not waste your time fitting new shells, they won't last very long.

Worth a look, certainly. Sorry to be nosing in, but I just know Onne will want a hand doing this, just like he wanted a hand putting the engine in. I kind of hope not, being in the middle of stripping a few engines and building another

Thanks for the advice. I hope I can get round to some ramps near here, that would be lush!

Onne

End float on the old crank is not fatal - worth considering using it in this block if it has good pistons and bores. Yes it means engine out - but all the bolts should come out easily!

There is end float on the crank of the current engine. That was one thing the old one didn't have, rumbly bottom end.
Just a miserable middle bit

End float happens with too long on the clutch pedal - wears the thrust washers on the crank - but highly unlikely to have actually worn the crank. These are not expensive. Sounds like you need your current block/pistons with the crank from the old engine. Take the good crank out and inspect it - and if it's in good order get a set of shells for it - and new thrust washers.

You may well find that the big end shells have huge pockets of metal missing. If so, replacing them will help oil pressure.
An additional 'easy'* way to improve oil pressure is to make sure the rocker shaft is good - if it is heavily worn you loose a lot of oil pressure here as well.
Quite often a Minor engine with poor oil pressure can get a good improvement this way. (People will tell you otherwise, but I've done it and could see the improvement).


* 'easy' - doesn't take days and doesn't involve taking the engine out etc..

Good advice, I'll have a look

An additional 'easy'* way to improve oil pressure is to make sure the rocker shaft is good - if it is heavily worn you loose a lot of oil pressure here as well.
Quite often a Minor engine with poor oil pressure can get a good improvement this way.

Sounds interesting could you expand on that a little.

Sounds interesting could you expand on that a little.

The rocker shaft gets worn and there can be up to 1mm steps in the shaft! When the oil is hot and engine is at tickover, the actual flow from the pump is very poor, and wih a rocker shaft like that you get so much flow/leakage of oil that the pump can't build up any pressure.

With the big end shells - I agree that a proper fix is only possible if the crank is in the correct condition however the pockets of missing metal create oil leakage paths. This prevents a continuous film when the oil pressure is low, therefore helping the main bearings be equally damaged (the oil pressure fed through the crank will affect main and big ends). replacing the big ends will reduce excessive oil loss and ntherefore help maintain a health pressure at the big ends and mains - this in turn helps the main bearings last longer.

I've seen Minor engines where the oil light comes on a tickover be dramatically improved with just these 2 changes and neither are an engine out job.
This does not mean that a knackered engine will run for ever and it is only putting off the inevitable rebuild/replacement but if you're on a budget it is always worth to add 5 or 10 years more life to a tired engine.

Agreed. If the crank is OK then a new set of shells does wonders for extending life

Though even with a poor crank you might be OK - I did the big ends on one of my Triumph 1500 lumps, after not long it was rattling again. Figured it was bin fodder, but when stripping it the other week I discovered the big ends had survived fine (even though there was a lot of wear on the crank journals), it was the mains that had worn out...

The rocker shaft is kind of 'grasping at straws' - but if it's worn it certainly won't be helping.

I have hopefully found a solution, maybe not ideal, but it is a 948, which appears to be quite good.

Austin engine, since it has the masking plate for the fuel pump

I bet this is yet another low compression engine

The rocker shaft is kind of 'grasping at straws' - but if it's worn it certainly won't be helping

Have you ever tried this or are you just guessing?
I've tried this to see the results - otherwise I'd not post about it.

If you want to base your answer on theory, please read up on hydraulics. (I have worked as an engineer at the pump division 'formerly Vickers pumps' in Bad Homburg, Germany - world leaders in automotive pump technology.)
Pressure is the same all thrugh the oilways when considering low flow and low viscosity fluid. Flow capability of the pump with hot (thin) oil at low speed (tickover) is extremely low therefore this assumption is justified.
Leakage through a pressure lubricated journal at a given viscosity and supply pressure is affected by many factors - including the working clearance, oil film thickness and effective length of leak path. The crank leakage rate is also affected by speed however as low speed is worst case for the pump capacity this isn't the most critical factor.

If you are capable to calculate all that, then you will understand why I roll my eyes and sigh at your response. On an A-series engine, a badly worn rocker shaft is one of the high candidates for minimal oil pressure.


By the way, whilst on the subject of bad advice, I sought out the engineers from Rover who worked on bench marking the effect of unleaded fuel in standard A-series engines. VSR is very easy to proove, however the biggest problem they found was wear in the valve guides due to the lack of lead lubrication. This creates significant oil loss - what is your experience of 'valve guide sealing' for your recommended approach of not using any fuel additive?

The thing is - the oil feed supply to the rocker gear is very limited - by the small diameter hole that feeds up there - and this not a direct feed- it's from the camshaft journal - and so - especially if the general pressure is low anyway - the flow to the rockers will not be great. However - if it is badly worn - and the wear mentioned earlier is massively excessive - then it certainly won't be helping. But the oil passageways to the main bearings are very much larger than the wee feed to the rockers - and so it really is not going to make a massive difference.
I find it hard to see how the lead from the fuel gets to the valve guides - but if 'experts' say so - then who I am I to query ? The inlets will see some fuel passing by - but they are under suction at that point - pulling oil down from the rockers (which is why there are seals on there) - and the exhausts guides see only burned gases - no doubt in the old days still containg the lead in some form or other - however to do it's 'anti knock' business the lead (from the Tetra-ethyl lead) will have been oxidised in the combustion chamber. My experience is simply from the University of Life - I don't add anything to the fuel in either my Mini or my Minor - and I don't have valve seat recession in either car. many others report the same. However - I have said in the past that neither of my cars does a huge mileage - but the worst that can happen is that the valves will recess over time , it's not a sudden thing and it's no major calamity. If that happens - then get unleaded seats put in the head - or start buying additive. The point is- for cars NOT doing big mileages and only gently driven - they will go on for a very long time before any signs of wear set in. This can be checked by inspecting the valve gaps - twice a year will suffice - and if the gaps start closing, then it's time to do something about it.
Valve guides should be sealed with rubber seals - the later inverted buckets are much better than the wee O rings - and they should not be fitted to the exhaust valves - just the inlets, this to intentionally allow some lubrication down the hot exhaust stems.