Boiled clutch hydraulics - Dolomite 1500!

[markas]

Got my Dolomite 1500 ready to take part in the CT Coast to Coast run this last weekend. In Peterborough - on my way to the starting point on Anglesey - lost the clutch plus much smoke from underneath and smell of burning brake fluid while waiting at traffic lights! Got the car to a safe place, found the fluid level in the clutch master cylinder had dropped only very slightly and the gears had come back so topped up the fluid and carried on. Lost the clutch again at the M6 tollbooth - could have been embarrassing but once again the gears came back by the time I had been relieved of my £5.90. It happened again on the run in the middle of Chesterfield, after the car had been running continuously for about 4 hours.
On checking the fluid at the half-way halt on the M1 it looked more like soup than clutch fluid.
I've had a Dolomite 1500 before which I used to drive quite hard and never experienced this problem. Current thinking to resolve the problem is change over to DOT 5 silicone hydraulic fluid for the clutch and possibly fabricate and fit a heat shield over the exhaust manifold.
Has anyone else experienced any similar problems and if so, what solution have you employed?

[Galileo]

I've heard of using washing up liquid as brake (hydraulic) fluid if in desperate times but never it turning into soap! When you say soap, do you mean lots of bubbles, like when old fluid gets hot and the water in it boils? No other symptoms then, clutch slip, exhaust leak, I'm thinking of extra sudden heat?

[markas]

I've heard of using washing up liquid as brake (hydraulic) fluid if in desperate times but never it turning into soap! When you say soap, do you mean lots of bubbles, like when old fluid gets hot and the water in it boils? No other symptoms then, clutch slip, exhaust leak, I'm thinking of extra sudden heat?

Soup rather than soap, but as you say, full of tiny bubbles. The fluid was changed only a few days earlier as the slave cylinder was shot and had to be replaced.
Certainly lots of heat around - the car did get stuck in heavy rush hour traffic in King's Lynn for about 20 minutes on Friday, which was a warm day - but no clutch slip before or after the event and the exhaust manifold is fine.

[Galileo]

A bit late and bleary eyed obviously!

Weird, I've only seen bubbles in contaminated fluid, don't think that fresh fluid can actually boil.

[Galileo]

Q&D research, boiling point of fresh out of the bottle DOT3 is 205 °C, I'd expect your seals in the slave/mc to have melted at that point!

[Carledo]

Saw a film about cars in Cuba and one guy was making his own brake fluid from hair shampoo (and other ingredients)

It is possible that if the garage left the fluid container open for any length of time, the fluid could have already soaked up water before it even reached your car! It's something i'm always careful about as I buy the stuff by the gallon and it can take up to a year to use that much! Easily long enough for it to become contaminated if not kept sealed!

If you want high temp fluid, DOT5 silicone is not the best, you want DOT 5.1 synthetic racing fluid.

Steve

[Galileo]

It might have been the same programme Steve, don't they also deliberately boil brake fluid to get the water out in Cuba? (And probably other countries lacking in imports/money!)

I reckon you're right, new fluid but maybe sitting around for a bit and took on a lot of water, can't remember the exact figure but 'wet' fluid has a drastically reduced boiling point, and would explain the visuals as well as the effects the OP mentions. I'm a slant 4 trick pony, does the exhaust run close to the clutch line on a 1500?

[markas]

Q&D research, boiling point of fresh out of the bottle DOT3 is 205 °C, I'd expect your seals in the slave/mc to have melted at that point!

The seals must have survived - at least for the most part - as the car did over 800 miles over the weekend, with the problem emerging on just three occasions, twice after lots of stop-start driving in town and once after a sustained high speed motorway run.

If you want high temp fluid, DOT5 silicone is not the best, you want DOT 5.1 synthetic racing fluid.

Steve

Thanks for that Steve, would DOT 5.1 be compatible with the seal repair kits sold by the usual suspects?

... does the exhaust run close to the clutch line on a 1500?

The problem is that the reservoir is part of the m/c and it's positioned directly over the exhaust manifold. Would it be possible to convert the 1500 set-up to a Sprint m/c with remote reservoir?

[Carledo]

Q&D research, boiling point of fresh out of the bottle DOT3 is 205 °C, I'd expect your seals in the slave/mc to have melted at that point!

The seals must have survived - at least for the most part - as the car did over 800 miles over the weekend, with the problem emerging on just three occasions, twice after lots of stop-start driving in town and once after a sustained high speed motorway run.

If you want high temp fluid, DOT5 silicone is not the best, you want DOT 5.1 synthetic racing fluid.

Steve

Thanks for that Steve, would DOT 5.1 be compatible with the seal repair kits sold by the usual suspects?

... does the exhaust run close to the clutch line on a 1500?

The problem is that the reservoir is part of the m/c and it's positioned directly over the exhaust manifold. Would it be possible to convert the 1500 set-up to a Sprint m/c with remote reservoir?

I've just drained out the old fluid and replaced with DOT 5.1 before now, certainly will work with new seals!

And yes, you could fit a Sprint clutch master and separate reservoir, but you shouldn't need to!

Steve

[TrustNo1]

I've never heard of this on a1500 or 1300 before being caused by the reservoir being above the exhaust assuming you have a standard exhaust. check the routing of the pipe how close is it to the block or exhaust or is something causing heat build up where the slave is (over packing of insulation not allowing heat to escape)
Rather than changing the fluid to another type you need to find what's causing it.

Also worth checking and can give the same symptoms, it happened on my truck but without the smell, is that the slave cylinder seal has gone and the rubber boot has retained the fluid that has leaked out, I admit its unlikely on the 1500 but worth checking.

[markas]

I've just drained out the old fluid and replaced with DOT 5.1 before now, certainly will work with new seals!

And yes, you could fit a Sprint clutch master and separate reservoir, but you shouldn't need to!

Steve

Good to know that DOT 5.1 would work with new seals, thanks also for confirming my thoughts that the Sprint mod would work. Another reason to do the mod is that the m/c on the 1500 is such a beast to get to... ended up liberating one of those little milk jugs you get with a cuppa in Tesco just for topping up purposes

Rather than changing the fluid to another type you need to find what's causing it.

I totally agree. However the car's not been modified from original in any way, other than having to replace the slave cylinder with one of the (not very good) pattern parts that are currently available.

Also worth checking and can give the same symptoms, it happened on my truck but without the smell, is that the slave cylinder seal has gone and the rubber boot has retained the fluid that has leaked out, I admit its unlikely on the 1500 but worth checking.

Good point and not impossible to believe that this could happen, even with a new slave cylinder. However, would the car then go on to cover another 800 miles with only a couple more hiccups in the same department?

[Galileo]

The seals must have survived - at least for the most part - as the car did over 800 miles over the weekend, with the problem emerging on just three occasions, twice after lots of stop-start driving in town and once after a sustained high speed motorway run.

What I meant is that if it was fresh fluid that had boiled, you would needed to have had temperatures that high, which suggests that the fluid 'aint all that, was the fluid you used out of a previously unopened tin?

[markas]

What I meant is that if it was fresh fluid that had boiled, you would needed to have had temperatures that high, which suggests that the fluid 'aint all that, was the fluid you used out of a previously unopened tin?

Good point and I don't know to be honest. However, it was a hot day and the car was stuck for a good 20 minutes in stop-start inner-city traffic about 30 minutes before it kicked off. Put the heater and blower on to bring the engine temperature down a bit (only reached 1/3 of the way up the temp gauge at maximum) but clearly that doesn't cool the exhaust manifold down which is directly under the m/c.

[TrustNo1]

Good point and not impossible to believe that this could happen, even with a new slave cylinder. However, would the car then go on to cover another 800 miles with only a couple more hiccups in the same department?

Yep when it happened on my truck it was several weeks and a lot of miles, a couple of fluid flushes where the fluid would go milky within a day and still losing a very small amount of fluid I eventually found the problem whilst checking the adjustment on the push rod I touched the rubber boot and fluid came out.

[markas]

Good point and not impossible to believe that this could happen, even with a new slave cylinder. However, would the car then go on to cover another 800 miles with only a couple more hiccups in the same department?

Yep when it happened on my truck it was several weeks and a lot of miles, a couple of fluid flushes where the fluid would go milky within a day and still losing a very small amount of fluid I eventually found the problem whilst checking the adjustment on the push rod I touched the rubber boot and fluid came out.

Was that with a new cylinder though? I would hope that a brand new item would be a bit more resilient than that