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MG MGA - oil flow ?

After starting engine after rebuild I have oil pressure but no oil to the head. I have researched archives and found disscusions of similar problems. I have removed rocker posts and have no oil coming up through head. I can insert a thin wire into the oil passage in head 3" an hit something. Does the oil passage hole go straight through the head which would mean the head gasket is blocking the hole?
C Tarr

CT, that's a strange one. At first I thought you may have put the head gasket on upside down, so I checked the spare Payen gasket I have and it appears that it would make no difference. The holes in the rear of the gasket are the same as those at the front. Of course, your brand of head gasket could be different, are you sure it went on the right way up?
Lindsay Sampford

I put the motor together several years ago and started it. Then I have worked on the body. I would start it up every few months to keep but have never had it on the road. I only discovered the problem when I went to do a final adjustment on the valves prior to adjusting carbs. It may be the cam bearing blocking the hole to the head as I did have the camshaft out. But has been to long to remember. I was trying to work my way from the top down. I don't know if the oil passage through the head is straight.
C Tarr

CT, just checked a spare head, it doesn't go straight through. The oil hole in the rear rocker pedestal is above the #4 combustion chamber, so there must be a cross drilling.
Lindsay Sampford

This page from Barney's site explains it. http://mgaguru.com/mgtech/engine/of101a.htm
Lindsay Sampford

Thanks for info. My next step is take off head.
C Tarr

Hole in the head does not go straight through. There is a cross drilling from the back end with a brass plug. The hole going from block to head is much closer to the back. Oil is fed from the main oil galley to the crankshaft main bearings. From there it goes to the camshaft bearings. From the rear cam bearing there is a vertical drilling to the head gasket where it transfers oil to the head. No oil to the head usually means the rear cam bearing was installed wrong and is blocking the passage of oil upward. See here:
http://mgaguru.com/mgtech/engine/of101.htm
http://mgaguru.com/mgtech/engine/of101a.htm
http://mgaguru.com/mgtech/engine/of102.htm
Barney Gaylord

CT, looks like you might be doing something with the cam bearing as well, ouch!
Lindsay Sampford

Double ouch!!
To Barney. I read on your site about removing camshaft with out removing engine. is it possible to fix bearing this way or am I looking at major pain?
C Tarr

Cam bearing puller looks like this:
http://mgaguru.com/mgtech/tools/ts206.htm

Pretty sure the only way to get the rear cam bearing out is to remove the engine rear plate and pull from the back. That means pulling the engine and a lot of disassembly. Follow instructions to remove camshaft (which could be done with engine in the car without removing the head). I think you can leave the crankshaft, con-rods and pistons in the block, and leave the front plate on after removing everything else up front to get the cam out. But then you have to pull the engine out of the car anyway to remove clutch, flywheel and rear plate before you can R+R the rear cam bearing.

If you were real careful you might do it without removing the oil pan (and oil pump). Need to R&R the distributor and drive gear anyway, because you need to realign the drive gear during reassembly. So not mix up the tappets. Be sure to put them back in the original locations to mate with original mated cam lobes.

When installing the rear cam bearing, look carefully at the drill hole from rear main bearing to rear cam bearing, and the drill hole going straight up from the rear cam bearing. Look also at the cam bearing itself, and orient the bearing shell so some holes will line up to allow oil to pass through or around the cam bearing to get to the top end.

This situation can be very disturbing if you paid some pro shop to rebuild the engine (or to machine the block and install cam bearings). It might be more of a kick in the butt if you did it yourself, but you gain good character and learn good lessons from the School Of Hard Knocks
Barney Gaylord

CT, before you pull it all to pieces, do make absolutely sure that you have no oil coming up to the head. If the rockers are bone dry, then fair enough, but if not, bear in mind that it may take a few seconds for the oil to be lifted up there. If you take the head off before you do anything else, you can give the engine a good spin on the starter to be certain that oil doesn't come up the oil way in the block. It would be a shame to go to all that trouble for nothing!
Lindsay Sampford

CT - You have got the rear rocker shaft pedestal, with the oil hole in, at the rear haven't you? ...and the holes line up? Sorry if I'm telling you how to eggs here, but pulling that engine is not the easy option..!
Specialists even get this one wrong!
Pete
P N Tipping

This engine was rebuilt by PO and was not in car. I don't know if it was done by a shop or not. I did have a main bearing in backwards. There was still assembly lube on various parts a few years back when I had the problem with the main bearing. I had the plugs out and spun the motor without the rocker pillar. no oil after several trys. Best part is i just finished getting the bonnet on and got the latch and release working. I have been working on car for almost 6 years. I had the motor running without the body on about 3 years ago but never realized the problem with the oil.
C Tarr

CT, If I was you, I'd strip that engine to the last nut and bolt and put it back together properly. I had the same suspicions with my engine, and when it blew the rear core plug, decided to take the opportunity to strip it down completely. I was glad I did, there was a list of things that hadn't been assembled correctly, let alone the bits that hadn't been replaced that should've! If you want a job doing properly, do it yourself!
Lindsay Sampford

Problem resolved. The cam bearing was in the correct position. The oil passage leading up to the head was plugged. It was just the last 1/4" of the passage right at the bearing that was plugged. Took about 2 minutes to correct but 2 days to remove engine. Now put it all back together.
C Tarr

2 Days to remove an engine is an eternity. It's feasible in less than an hour if you are organised.
dominic clancy

This thread was discussed between 26/07/2011 and 17/08/2011

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