Cool Runnings

fd · Post by fd » Thu Oct 15, 2009 11:32 am

Uh huh, but that's the thing . . . thermal cycling of the head is one of the (many) things cited as being an HGF inducer . . . and it seems (as in your experience) many PRRT installs are actually worse for that than the standard 'stat install . . .

In normal driving my nornally 'statted car sits at 86C +-1 which is very stable (if you ignore earthing induced 'temp changes'), when ragging the nuts of it to the rev limiter it drops a couple of degrees then very quickly settles back at 86C, probably within 5 seconds, it's always done this apart from when the 'stat was faulty when it dropped a lot more and ran cool . . .

If you have gas in the rad, however, temperature control is much worse . . . hence why I always say to check the rad for gas and bleed it to perfection . . . gas in the rad effectively partially blocks it and must do something to the flow in the cooling system that sets up incorrect behaviour . . .

Anyways . . . it's a pain to change the stat but necessary, whether a PRRT gives any benefit is open to debate . . . with my car I can't believe it could be much better than it is . . .

$0.02

Fd

Ferg · Post by **Ferg** » Thu Oct 15, 2009 12:14 pm

I've not owned a car with such a remote rad before. Is bleeding just a case of releasing the top? hose to get air out.

I obviously need to sort out a manual....

fd · Post by fd » Thu Oct 15, 2009 12:25 pm

Ferg wrote:I've not owned a car with such a remote rad before. Is bleeding just a case of releasing the top? hose to get air out.

I obviously need to sort out a manual....

No, there is a bleed point on the rad exit (pax side) at the very front of the car where the pipe exits the rad, it's a small screwed bleed, get the car nose up and pax side up and bleed it until it runs coolant, you will have to do this a number of times to get it all out . . . you don't need to completely unscrew . . . you can reach it by pushing back the rad shroud and reaching in, no need to remove anything to get access . . .

There is also a bleed point on the metal pipe that runs to the thermostat, at the number 4 cylinder end of the engine, obvious, small 8mm bolt, do this one first when you fill the car after draining it . . .

I'd put a copy of the pdf manual online but I'm not sure where I have a copy apart from on my mac which has just croaked . . . someone will no doubt oblige . . .

Fd

tut · Post by **tut** » Thu Oct 15, 2009 12:33 pm

As FD says, make sure that you do not undo the bleed screw all the way out which is easy to do, as the last thing you want is it dropping down inside.

I have a copy of the manual Fergus, but not sure if we are allowed to post it on the Forum. I could e-mail it though.

tut

Rich H · Post by **Rich H** » Thu Oct 15, 2009 1:07 pm

Old S1s haev a coolant rail over the exhaust manifold on the firewall with a beedpoint - just for completeness

Ferg · Post by **Ferg** » Thu Oct 15, 2009 1:47 pm

Great info again. Looks like I'm going to be getting the spanners out sooner than planned. Haven't quite worked out how I'm going to break it to the wife that I need to start taking the expensive new car to pieces.

Tut, you have mail.

Corranga · Post by **Corranga** » Thu Oct 15, 2009 2:25 pm

Ferg wrote:Tut, you have mail.

Advice PM'd...

Chris

Baggy · Post by **Baggy** » Mon Oct 19, 2009 2:14 pm

I kind of half agree with fd and I have a PRRT fitted.

Initially i had temp fluctuations but this (i think) was caused by the cream stat (as per rich's photo)
combined with phantom air getting into the system which stopped when i replaced the old heater matrix.

latest recommended to use is grey stat with weaker spring. I now have this and it works fine.

Thing is though that my understanding of the benefits of fitting the PRRT wasn't necessarily to steady the temps but was more to move the hot/cold water interface point when the stat opens away from the head. Don't forget that the prrt wasn't initially knocked up by some bloke in a shed. Landrover developed it because of the issues they were having with HGF on the k series freelanders. the issues that elise owners have been having with fitting them is largely because they are butchering kits and hoses not designed for the car.
Initially I kind of regretted fannying with the cooling system that was working perfectly but now the prrt is fitted and sorted I'm glad it's there and I think now that geary is marketing tailor made hoses I personnally wouldn't hesitate to go that route.

Ferg · Post by **Ferg** » Mon Oct 19, 2009 4:53 pm

thanks. got the sensors on the way. Going to bleed the system properly too and see where I am from there.

Ferg · Post by **Ferg** » Sat Oct 24, 2009 5:39 pm

Fitted the sensors today and it looks like it sorted. I also went through the secondary bleeding process in the manual and it released a little air from the system.

The temperature now runs bang on and when left to heat up the thermostat worked as decribed in the manual and the fan came on perfectly. Fantastic!

I can now relax about running in traffic and also maybe give a bit more beans now I'm happy it's running right.

So thanks, Dan for suggesting sensors in the first place and everyone else for their input.

Scottish Elises

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