75 CDT - Engine too warm

[goltho]

Originally Posted by T-Cut

Yours is the very first report (that I've ready anyway) of this effect. As noted, your warning should be taken on board by diesel owners with in-line stats. On the other hand, it may never happen again.

TC

Duly noted. I picked up an inline stat & hose clips this morning in preparation for fitting this week (temp rarely goes above 59ºC according to 7.1). Potential ticking time bomb is correct irrespective of how likely or unlikely.

Dougie.

[T-Cut]

Originally Posted by slovcan

Why not do the work and remove the original thermostat, then install the inline 92 degree thermostat? In the future replacement will be easier.

That would logically be the ultimate fix. But the original idea was to avoid doing any work on the old stat and simply insert the in-line one as a quick and effective solution. Working on the original usually involves replacing the standard stat. But the basic question remains, how long will they last?

TC

[goltho]

Originally Posted by T-Cut

But the basic question remains, how long will they last?

Might it not be worth considering an aftermarket "original" stat from a different manufacturer to the one(s) who supplied the factories? It surely can't be a universal foregone conclusion that the design of the engine causes all stats to fail in this way. What did BMW fit?

Dougie.

[Daveluck]

Originally Posted by goltho

Might it not be worth considering an aftermarket "original" stat from a different manufacturer to the one(s) who supplied the factories? It surely can't be a universal foregone conclusion that the design of the engine causes all stats to fail in this way. What did BMW fit?

Dougie.

You can buy just the thermostat insert. They just squeeze and twist out. But don't forget their appears to be 2 OEM thermostats fitted to diesels. The one fitted to early diesels appeared to last considerably longer than the mk2.

Whether you could buy a BMW thermostat housing and then possibly remove the thermostat and fit it into the old housing?

Right now, as far as my limited desire to investigate any further, there only appears to be chinese chaps producing these. As to who they are supplying...well I guess pretty much everybody that sells the thermostat And where would the BMW ones be coming from?

Definatley nothing to do with the engine design. That is superb. Just like the BMW turbo failures were not down to the engine design.

For me I think the way to go if this one fails will be to buy the machined inline thermostat housing and remove the rover thermostat gubbins from the housing and refit. That at least will give you a better and wider choice of thermostats and should mean easier replacement

[goltho]

Originally Posted by Daveluck

For me I think the way to go if this one fails will be to buy the machined inline thermostat housing and remove the rover thermostat gubbins from the housing and refit. That at least will give you a better and wider choice of thermostats and should mean easier replacement

Agreed. That would eliminate the possibility of the stuck-open stat eventually closing after the inline solution was fitted and therefore the potential catastrophe as discussed above. The downside of course is that it also eliminates the ease of the inline solution by still having to do the work it saves.

Dougie.

[slovcan]

Originally Posted by goltho

Agreed. That would eliminate the possibility of the stuck-open stat eventually closing after the inline solution was fitted and therefore the potential catastrophe as discussed above. The downside of course is that it also eliminates the ease of the inline solution by still having to do the work it saves.

Dougie.

Only the first time.

Cheers,
Glenn

[Comfortably Numb]

No temperature problems at the moment on my CDT, - it produces warm air after around a mile of country lanes, and proceeds to a rock-steady 9.00 clock position on the gauge. Are we saying that the failed shut scenario is only likely to happen if an in-line stat causes it to get overcooked for too long, so the seal perishes and lets the wax leak out? I'd rather my stat failed open, and let the engine run cold. My daughter's Polo had a stupid plastic stat that failed in the shut position (the plastic 'bridge' that held the spring pressure inevitably aged and broke, so the stat shut with a bang on the motorway). Result (luckily) only a new head gasket, she saw the temp warning light come on and pulled over on the hard shoulder - well trained!

[goltho]

Originally Posted by slovcan

Only the first time.

One time too many.

[T-Cut]

Originally Posted by Comfortably Numb

I'd rather my stat failed open and let the engine run cold.

You won't find one. Not for a 75/ZT anyway. The so-called 'fail-open' type are a special design which latches the valve in the open position if the coolant exceeds a preset maximum temperature (Google or YouTube it). Most common stats fail closed because they don't have much option. The high tension return spring sees to that. Very occasionally, a stat will 'fail open' due to mechanical fouling of the valve, but that doesn't count. The usual symptom of a failed stat is rapid overheating, but a wedged open stat will prevent the engine ever reaching normal running temperature. A common cause of stat failure is ejection of molten wax through the piston seal and consequential water ingestion into the capsule. The driving force of the wax is then lost and the valve will never open again.

TC