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MG MGA - Engine Mount Rubbers

I am in the process of removing the engine for a general inspection, repaint and clean-up in the engine bay. I will also take the opportunity to lighten the flywheel, replace the clutch plate etc.

However, one item that we discussed about a year ago is the engine mount. My engine seems to be sitting a smidge low; the pulley only clears the cross member by about 3/8" and the cranking hole does not line up with the over-rider (bumper) hole. I enquired of Bob West (James in fact) and he said that the current Chinese rubber mounts are too hard (wrong grade of rubber) and they cause engine vibrations to be transmitted through the car. Anyone experienced this? Any alternative suppliers of good quality mounts that you can recommend?

Steve

Steve Gyles

Steve,
My crank handle didn't line up either, so I used a wooden dowel centralised on the bumper hole and the crankshaft nut and found the obstruction was the bracket abot midway between - just made the hole in this bracket a bit larger with a Dremel grinder - now the crank handle works (not sure if this will solve your problem!)
Regards
Mike
Mike Ellsmore

Hi Steve - good luck with your engine removal etc. I replaced the engine mounts a couple of years ago when one of the brackets sheared. I noticed that there was more vibration after the new mounts were in but don't notice it so much now - either I have got used to it or the rubber has softened up - cheers Cam
Cam Cunningham

Thanks Mike. It's not so much that I need to crank the engine! It's just one of the clues that all is not what it should be. The biggest problem has been the clearance, or lack of it, between the pulley and the crossmember. I had trouble getting the fanbelt on when I last replaced it. It might also be an issue when I add my supercharger (wife is softening!).

Cam. Maybe you have one of the engine mounts James referred to.

Steve
Steve Gyles

My first clue that the cause is the engine mounts: I have just looked at my invoices for the rebuild back in 1997. It appears that I did not replace the mounts then. Before that the car had been in a barn for 22 years. Seems I could be using the original mounts from 1958! Oh dear, give my hand a slap, not good engineering practice! Put it down to experience, or lack of it at the time.

Steve
Steve Gyles

I just installed my engine using the mounts that the PO had purchased from Moss. The mounts seem OK (don't have the screw-breakage problem that Barney mentions) but I did notice that the left one was bent and not lining up well. This caused the rubber to be twisted and also effected engine alignment. I bent it about 98% of the way back and it's OK now. I really should order a new metal bracket (this is the bracket that mounts on the engine).

Your rubber should almost certainly be replaced - but take a look to see if your brackets have suffered similar trauma - that could be another source of your trouble.
AJ Mail

This was the broken bracket on my engine mounts - when it went it felt as if the whole car was going to shake itself to pieces - cheers Cam

Cam Cunningham

AJ

Looks like my problem as well. Now that I have stripped away the ancillaries and I can get a good view of an engine mount it looks a bit bent.

You can also see why I am pulling the engine for a general clean up. A few oil weeps to to sort out.

Steve

Steve Gyles

I have had the original 1600 and a b engine in over time and used new rubber both times I must say that my mounts were both times cranked like your picture I would say that is not a proplem. thet look quite solid. but obviously best to replace. I would like to take a bet that if you replaced the rubber it would still be canted likr it is now.


David

David swaine

David

It's the 'L'-shaped bracket above the rubber that I am concerned about. It would seem that over time the weight of the engine has opened it out beyond the 90 degrees. I spoke to Bob West about it this afternoon. I am not sure that you can get new brackets. It looks like a job for the vice, heat and hammer.

Steve
Steve Gyles

That is exactly my problem as well! Same side, too! Mine was even a bit worse than yours and banging it got it to a bit better than where yours is now - it kept wanting to bend in the middle rather than get any flatter when I had it in the vise...a torch might help here.

I should probably take mine out and try again, as it does seem my engine (to my eye, no one else would notice I don't think) is the slightest bit off kilter in the frame. Before I noticed this I had measured the frame a number of times, sure that that was the bent part - but it appears straight. At least the engine mount is easier to fix!

AJ Mail

I believe the bend is due to the engine torquing over when it is running. As a reaction to turning the driveshaft the engine tries to unwind itself and this is resisted by the engine mounts. I don't know what would happen if you reinforced the plate.
John DeWolf

I wonder why both engine mount brackets vary in layout. The right hand bracket is 'L'-shaped on its back, while the left bracket is face down. With engine weight and torque, one bracket opens the angle greater than 90 degrees and the other closes. Is there some specific engineering reason for this?

Steve

Steve Gyles

Interesting observation Steve. By the way - if you need a second pair of hands to help pull your engine , give me a call - I'm only half an hour away - cheers Cam
Cam Cunningham


Steve

My guess (and that is all it is)would be so that both supporting flanges are in tension when resisting rotational forces and thus prevent buckling of the flange that might be caused by having the RH mounting flange in compression as it would be if it were turned down to match the LH.
Of course the result is the LH leg bends instead. I would imagine the reason it is the left side that bends is because on that side the forces are made up of the rotational forces of engine torque plus the weight of the engine, while on the right side it would be the rotational forces less the engine weight. On one side gravity is working with rotation while on the other side gravity is working against rotation.
John DeWolf

Cam

Sorry missed your offer. Pulling the engine is a straight forward one person job, given the right equipment. However, I would have nearly eaten my words this afternoon when my hydraulic crane would not pump high enough initially for the sump to clear the body. Probably lack of use with the pump seal was not doing its job. Sorted after about 5 raises and lowers (Robert The Bruce springs to mind).

Lots of issues with the engine on initial inspection, quite apart from the engine bearers. Looks like water seepage out of the head gasket; a few oil weeps; and the drainage tap water way looks blocked. Should keep me occupied for a few days.

Steve
Steve Gyles

The brackets are backwards just because of the shape of the front plate, dictated by the timing chain/tensioner.

Look for cracks in the 90 deg bend. The distortion is partly just loading and age, but is made lots worse if the bottom bolt is loose or missing at any point in the car's life. I use a big thick flat washer on the bottom bolt. You can also prestress the mount bracket favourably after you get it straight, by putting a flat washer between the block and the bracket at the lower bolt. The two flat washers generally call for a longer bolt. I started doing this to prevent the brackets breaking on late MGB, which have a serious problem here. Works great!

FRM
FR Millmore

FRM

I know what you are saying about the front plate, but is it not a case of which came first - the chicken or the egg? I would have thought that they would have shaped the front plate extremities to accommodate the engine bearers in their optimum position. For example, the MGB front plate accommodates the same size chain cover but has a different shape at the edges to suit the MGB mounting plate.

I will look at your flat washer tip when setting the brackets.

Steve
Steve Gyles

Steve-
Really can't see an engineering/stress related reason. I expect that you could eventually figure out that there is some sort of layout advantage in stamping out the parts to best use of raw material. This is a very big thing in manufacturing, and frequently determines how parts are shaped. It can change a lot if they get a different machine, that say, lets them stamp out bits a 1/4" closer to an edge, which then changes the "nesting", which results in a 3.5% decrease in material cost, etc. Then you throw in the interchangeability between different uses of the same part, and all sorts of odd things happen.

FRM
FR Millmore

FRM

You are very likely right. Just had another look at mine. They are both folded the same way. Only the folding of the engine tabs makes them 'handed'. That said, the left side bracket has a curved edge to match the contour of the front plate. So it may all have been down to the convenience of the folding machine.

Also, you are right about the position of the front cover allowing only one possible position for the left bracket.

Steve
Steve Gyles

Just to put closure on this thread. I have put the engine back in after a cosmetic overhaul. This included new engine mount rubbers and bending the engine brackets back into shape. The engine now sits correctly and, for the first time in a dozen years, the cranking handle holes now line up. I was able to use the handle for the first time ever to set up the static timing for initial fire up.

The engine is running fine. Now back in doors to thaw out after 6 hours endurance in the garage: minus 6 for most of the day out there! Bit cold for this part of the world.

Steve
Steve Gyles

Post a picture of the rebuilt/cleaned up engine!

JIM
AJ Mail

Well done Steve. Hope to see the result of your labours in the New year - cheers Cam
Cam Cunningham

Missed this thread first time around so thanks for bumping it back to the top. Mine has been sitting low even with new rubber mounts so that the hand crank barely fits. Wouldn't have thought that a bend that slight would cause the problem but will have to try pulling and straightening mine.
Jeff Schultz

Jeff

I was surprised too. The engine is a good centimetre or so higher. Plenty of clearance now to get the fanbelt onto the bottom pulley.

Jim, reluctant to post a picture, I have my pride! It's been a working car, not concours. It was essentially an inspection job, plus a lick of paint. I will think about it.

Steve
Steve Gyles

This thread was discussed between 12/11/2009 and 21/12/2009

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