Stop Leak Products

[saljo]

Good day,

My much cared for and owned since new Elan S4 has suffered an irritating clutch judder for a while now.

The clutch is relatively new (30,000 miles), so I’m pretty sure the problem is a leaking main bearing seal, particularly as the judder worsens when the engine heats up and burning off the clutch plate by harsh use, buys a few more smooth months: obviously I don’t like doing this..

I’m hoping to delay pulling the engine to replace the seal/clutch and wonder if I can safely delay this by adding one of the various makes of ‘Stop Leak’ such as Lucas, AT-205 etc. to the engine oil. I’ve always considered such products as snake oil and anticipate a loud no/no from the engineers on here.

Online research is of little help with numerous conflicting opinions and no authoritative test results I can find. I don’t mind spending a few pounds to try it but clearly don’t want to risk the engine. Any thoughts much appreciated.

Cheers,

John.

[2cams70]

Are you sure it’s due to a leaking rear main seal? As the seal is behind the front face of the flywheel normally leaking oil is flung outward from the rear. It doesn’t tend to reach the front face where the clutch is. Was the flywheel correctly resurfaced the last time the clutch was replaced? I assume it hasn’t been slipped excessively.

[alan.barker]

+1 always resuface Flywheel when fitting new Clutch no matter how good it looks or how shiny it is. Been there done it.
Many times the Clutch judders more when you reverse .
Alan

[512BB]

Personally, I doubt the clutch judder is down to a leaking rear crank oil seal, and I also doubt that adding any mixture to the engine oil would cure a leak even if there was one. Furthermore, I would not take the risk of messing up an engine with such an additive.

The clutch in an Elan of mine started juddering on about 30k miles, only occasionally. So after it had covered 40k miles I removed the engine to sort out the miriad of oil leaks and to see what was up with the clutch. I resurfaced the flywheel, refitted the original clutch plate as there was nothing wrong with it, but more importantly, I cleaned the splines of the input shaft of the gearbox which were caked with old grease, and cleaned the splines of the clutch plate. That allowed the plate to slide freely on the shaft again, after applying a little fresh grease. No more judder.

I think you will find that if you carry out the same procedure, you're judder will be no more.

Leslie

[david.g.chapman]

+1 on resurfacing the flywheel. I had mine done on a recent clutch change, and for £60 it's a no-brainer.

Another thing that might be affecting things is any runout on the flywheel. I had 4 thou (on the limit) when I last changed the clutch over 15 years ago. I thought it was OK at the time. However, It had been juddering somewhat since then and I had lived with it.

When I did the clutch recently I took the time to try out all of the positions of the flywheel on the crankshaft. I found that one position gave me 2 thou runout, so I went with that and have no judder on reassembly.

I strongly recommend you do something similar...

Dave Chapman.

[mbell]

I can't speak to stop leak etc specifically but one interesting thing I recently found out is one of the differences between regular and high mileage oils are addictives designed to soften and slightly expand rubber seal materials to prevent leaks.

My guess is stop leaks are similar but stronger versions of that. So probably only help with minor leaks.

[reb53]

but more importantly, I cleaned the splines of the input shaft of the gearbox which were caked with old grease, and cleaned the splines of the clutch plate. That allowed the plate to slide freely on the shaft again, after applying a little fresh grease. No more judder.

I think you will find that if you carry out the same procedure, you're judder will be no more.

Leslie

I would second this.
It was exactly, ( and all), I did to fix a clutch that was of the "light switch" variety.
Nothing, nothing, nothing, then full engagement.
It also tended to stay engaged even with the clutch hard down.
Slightly disconcerting, especially when reversing....

As to the "Stop Leak" products.
Rather dubious after using a similar product on my wife's Fiesta in order to stop a very slow radiator leak.
Within about a month top and bottom hoses blew after they'd swollen hugely, and then split.
They looked like one of those pictures you see of a python that had a goat for lunch.....
I came to the conclusion that the product had softened, and swollen, the rubber in a vain attempt to do the same to the place that was leaking.
Not sure I'd want all the oil seals in my engine doing the same.
Unless of course I was selling it......

Ralph.

[69S4]

In their place I suppose they do have a purpose. We had an oil leak from the steering box of our becoming elderly Land Rover some years back and a bottle of the stuff stopped it long enough to get it through the mid winter MOT and through to the next summer when I could change it in the sunshine. Nothing like a permanent fix but ok where the consequences are acceptable

[2cams70]

Those engine stop leak products “work” by swelling rubber seals that have become hard due to age and heat. You therefore have absolutely no hope of it working if your engine has a rope type rear main seal.
The “stop leak” you put in your engine is certainly a different type of “stop leak” to the one you put in your radiator. If you put engine “stop leak” into your radiator that certainly would have some interesting effects!

[saljo]

Thank you all for the interesting replies.

It does look like an engine out job to see what is going on. Old grease on the input shaft splines does look like a possibility as well as an out of true flywheel - or both. There is no rush on this as the judder is managable and dosn't seem to be getting worse.

With replacement engine/gearbox/back axle mounts and lotocones, what lead me to suspect oil contamination of the clutch plates is that after a few brutal starts in top gear I get another few thousand miles of smooth operation, and a few thousand less of clutch life!

Anyway, I've been warned off Stop Leak as I suspected.

Thanks again and if/when I get round to removing the engine I'll report back.

John.