MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Oil Consumption/Burning

Thought I would start a new thread since my problem is a little different than the other oil burning thread. My '64B has the early 3 main (18G) engine, which has performed well in the 13 years I have had it on the road. Prior to putting it back on the road I had new valves & hardened seats installed, and I have put about 9,000 miles on the car since. It took awhile for the rings to get seated, but compression has been consistently 155-165 for the last 13 years, with minimal difference between the cylinders, and it is still at that level today. The cylinders read 1/160, 2/162, 3/153, 4/150, which are cold readings with the throttle open. The spark plugs show no signs of oil and are all consistent. Recently, oil pressure has been significantly lower and oil consumption considerably higher, until this week it was 1 quart in 250 miles. Also, there is a persistent smell of burning oil and the infrequent blue smoke out the tailpipe when accelerating after idling at a stop light, particularly until the engine is warm.

The picture I have included shows the bottom of the head, the top of the block and the spark plugs. Does anyone see anything significant? Suggestions are welcome!

Also, one of the water passages in the center of the block is closed off, but is open on the head and the head gasket. Is this correct?

Don

don scott

Looks like lots of oil 1 and 2, so much oil it has soaked off the carbon deposits on edge of piston crown. I would guess the bottom end is past best. Looks like oil soaked deposits on no1 combustion chamber squish areas. Is there a big lip at max height top ring in the bore?

Peter
Peter Burgess Tuning

Peter - thanks for your comments, the bottom end was my first suspicion as well but there hasn't been any noise coming from there. To answer your question there is not a big lip on cylinder 1 or any cylinder for that matter.

Don
don scott

How many miles has the bottom end done? Why should you have noise from the bottom end if rings are shot?

Peter
Peter Burgess Tuning

Sorry Peter I misunderstood what you were referring to by "bottom end". Would the compression readings still be high if the rings were shot?

Thanks for your help,

Don
don scott

As an update I have cleaned the top of one of the pistons in order to determine what is actually in the car. The marking on the top is MOWOG in the center, 4935061/1 opposite the front, and a 3 inside a diamond just under the above number. Am I correct that these are grade 3 standard pistons and the engine has not been bored before?

Don
don scott

sounds like it is standard. Oil contamination tends to give nice high compression readings.

Peter
Peter Burgess Tuning

Thanks Peter, sounds like it is time for the full rebuild I was planning to do over the winter.

Don
don scott

When you do a full rebuild use OEM iron piston rings if you can find them. The rings in you engine are probably original and that is why you don't have a ridge. They are slightly softer than the cylinder bores and you generally don't get a ridge because the iron rings do not wear the bores as bad

Peter can probably tell us if they are still available. I believe the brand is something like "Hep-o-lite"
Richard Smith 1

Unlikely to be the same material or even design these days.

Peter
Peter Burgess Tuning

This thread was discussed between 09/08/2015 and 31/08/2015

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now