R12 leaky sump

S

Stuey

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Hi Renfans,

I've got a problem with a leaky sump on the R12. Am I wishing too hard to hope I can do it with the motor in the car? I've had two good goes at it and failed. Any hints?

Cheers

Stuoily
 
Stuey,

I've done it successfully with the R8 and the 4CV. The R8 is dry underneath from the sump (not completely dry from the gearbox! The 4CV drips a bit but they do.....

All I can say to be helpful is that with the R8 I took a lot of care at the corners where the rubber bits fit under the cork bits at the bearing housings and I stuck the cork down (I mean up!) to the block with something or other. Maybe I used silicone? It was in about 1988! Haven't needed to touch it since.

I didn't think of it at the time, but a bit of superglue in one or two places to get the rubber bits fitting in the groove might help, but you'd need to be careful to have the rubber exactly in the right spot or it might do more harm than good.

It's a good exercise in self control, because if you loose your temper you bang your head. It would be nice to do it standing up on a hoist.

Of course if you pulled it out, you could replace the rear crankshaft seal and the front gearbox seal - no point in lots of fussing over the sump if the adjacent parts leak.......

Good luck.

(See you at the Classic Car Day on March 17th?)

JohnW
 
John,

I stuck them in place with top quality Loctite silicone both times. Suppose it's just a luck thing, when the engine's in the car. Have to try again, though; it's really bad. I don't suppose gasket brand matters? I just got whatever Caravelle sells. Do you silicone all the paper gasket on both sides too?

As for the Classic car Day, is that the event they also refer to as the French Car Day?

Cheers

Stuey
 
Hi Stuey,

With the gasket, make sure you use the right rubber pieces, with the set there are generally about three parts in the gasket set for the rear main bearing depending on whether the car is a 10 or early 12 or late 12.

I never use silicone or gasket stuff, generally high temp bearing grease is sticky enough on the surfaces and doesn't go everywhere. It also makes it easy when it becomes time to pull it apart, hopefully never :).

As John says, the rubber front/rear pieces go on first, followed by the gasket, also as John says you may want to blob silicone where the rubber meets the gasket, but I've only done that once and they seem to stay leakproof. If only the driveshaft seals were as leakproof!

As for accessing the sump, drop the anti rollbar by undoing the nuts where they attach to the chassis rails, even better remove the two nuts at the base of the shockabsorber and slide the whole thing off DO NOT REMOVE THE SHOCK ABSORBER BOLTS! Then pull off the cross bar between the chassis rails. The anti vibration bar at the front of the motor can also be pulled off It gives a bit extra space (two bolts attaching it to motor, and two nuts attaching it to the engine mounts behind the big weighty things, then slide off forward). Access to the sump bolts is easier using a 3/8 set with long extension bar, but it does come off fairly easily.

As for a magnet in the sump, I'm not too sure if it is really necessary. It may not be worth the hassle of putting one in.


Simon
 
Thanks for that Simon. When I said I'd had two good goes at it, I meant that I'd replaced the thing twice and it still leaked, not that I didn't get it done...Yeah I noticed the different seals in the kit - I just matched old with new; don't think there's a problem there. I took the anti roll bar off, but I didn't take the engine vibration thingy off - might try that next time.

As it happens, I did my clutch a while back and replaced the driveshaft seals, and they are absolutely dry and leak free about a year or so later. I polished the sealing surface with very fine carborundum paper (ie. wet or dry) till they were gleaming, and sealed the rollpins with silicone after scrupulous cleaning with carby cleaner around the rollpin hole. Worth the extra effort.

Cheers

Stuey
 
Stuey,
Working on 12s all the time I have learnt not to assume the way they come off is always right that may be why it keeps leaking if one gasket ect is not correct might pay to get a manual or similar and check ?????
 
As for the Classic car Day, is that the event they also refer to as the French Car Day?

Stuey - no it isn't. French Car Day was a few months back at Guildford. Classic Car Day is huge and at Whiteman Park - all brands, even BMC allowed!!

JohnW
 
Apprentice,

Yeah, checked the manual too at the time! One step ahead of ya there! I've seen some shockers in my time, and I'm not even a mechanic...

John,

I thought it was different - I just don't want to miss the French day. I might go to the Classic Car event. My FIL goes - he's got an ex Robert Menzies Rover P5 and the E-Type, and wants me to go each year...

BMC? Nothing wrong with BMC - I'm a fan, actually - my Dad worked in one of the Birmingham factories for a while.

Cheers

Stuey
 
Stuey,

Where is the sump leaking from? It just seems weird if you have had two goes and it still leaks. The only problem areas seem to be the corners between the rubber and fibre gaskets.This may be a silly question, but is it the front crank seal, rear main bearing seal or input shaft seal??

Another thought with the magnetic sump plug. Messing in the shed earlier I found a Pug 504 diff drain plug with magnet. It is an 18mm thread and seems identical to the R12 sump plug except that it has an 8mm square socket instead of the 10mm square socket of the 12 plug. I've not got a spare 12 sump to try it, but it did fit into an R4 sump which has the same thread. Could be worth a try, but I'm still not convinced a magnetic plug is necessary :)

Simon
 
Simon,

My two recent posts have melded into one...

What I thought is that the worn valve guides may have been pressurising the crankcase/rocker cover and forcing the oil out. The rear main seal and input shaft seal are OK (when I did the clutch, I replaced the input shaft seal), BUT the front crank seal is leaking despite my having the sealing surface on th pulley turned down and and undersized matched seal being fitted (so much for my clever idea, John W!).

Hence, my hypothesis is that the pressure in the sump is high... I was particularly fussy with the sump gaskets (I am with every job I do).

The blokes that did the engine rebuild didn't bother with the head...

Might just wrap the engine in a garbage bag :)

Cheers

Stuey
 
Stuey
Sounds to me like a simple case of blow by, doesn't matter who built your engine if the rings havn't bedded in properly your going to get blow by and know matter how many knew gaskets and seals you use the excesive pressure will find the weakest link and leak.
Keep plugin away.

David.
 
Those valve guides must really be gone if there is that much blowby, and assuming that the rings have seated as David points out. Try cleaning the breather hoses from the air cleaner to the rocker cover and to the base of the carby. They can get blocked with oil residue on an old motor and cause pressure. Check the plastic elbow on the rocker cover too, that could also be blocked, and if really bad the rocker cover too. Beware with the elbow, it is likely to be very brittle and eaily broken!

Another sneak that you may be able to get done, is knurling the existing guides, they can then be reamed to suit your existing valves. Best to get new valves too if they look a bit dodgy, otherwise you may have to do the job again sooner than you want. Depending on how long you want to keep the car it is better to save up and do the job hoping that it doesn't have to be done again for a long time. New guides and valves should do that.

With the rear main seal, there is a Renault dodge of just pushing it in a bit further than the original seal so that the new seal edge runs against an unworn area on the crankshaft. Could it be that the new seal is now worn slightly, and is running in a groove from the old original seal??

The only motor oil at the rear of the motor can come from the rear main, or the oil gallery plug (which rarely if ever leak if untouched) and I suppose if someone has bolted a 1.4 big rear main bearing sump to a 1.3 motor small main bearing motor. Tha above assumes that the sump gasket is currently correctly seated :)

As for the tripod, just try and take any pictures close to a handy wall for the next couple of months :)

Simon
 
Hi again,

Simon, I cleaned the breather system a while back.

Are you guys suggesting that the bores might have glazed before the rings were seated properly? I ran it in pretty carefully...

With the guides, why are the repair sizes bigger? Do they get loose in the head?

Thanks for all the help...

Stuey
 
Usually if the bores are glazed a motor burns oil all of the time. Yours doesn't sound like that but the pressure build up seems odd, was it a full piston/liner rebuild or just rings inside the existing liners? If the latter perhaps the clearances are too large or liners worn off square, allowing blowby but not enough for a smoky motor.

A good test for guides is with a warm motor, accelerate hard in 2nd or 3rd, to say 5000rpm for about 5 seconds, then suddenly decelerate (don't touch brakes) to suck oil down the guides, if the guides are worn there will be a lot of blue smoke behind the car!

No real explanation behind the larger service guides. Possibly it is a sort of belt and braces thing in case pushing out the old guides marginally increases the tolerances for a standard size guide. I've never known them to get loose in the head.

Simon
 
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