Replacing the thermostat!

Post by **Multiphonikks** » Tue Jun 29, 2004 9:33 am

After being plagued with all the problems with Hebe constantly overheating, I managed to purchase all the replacement parts and conned Pyoor_Kate to stay on Sunday to help me fix them on.

Easy (according to the Haynes manual). Undo the three bolts on the Thermostat housing, remove housing and old gasket, and remove old thermostat.

Ha!

Thanks to Pyoor_Kate's friend John, (who had come along for the weekend for fun,) we came up with a method of removing the thermostat housing which went thus:

Undo the three bolts. (easy)

Pour Waitroise toilet cleaner (the one which has limescale deposit acid) and wait for the accumulated gunk which is holding the casing firmly down to disolve.

Remove the Thermostat housing and gasket.

(Which took all of five hours because of all the accumulated gunk. We (naugtily and somewhat riskily) managed to use various screwdrivers as drifts/gasket removing tools, but of course you have to not condone this practice as you really do *&^% the bottom surface of the thermostat housing. (of course, we could have used a lock-nut method)... Having said that, damaging the thermostat hosing which already had a huge chunk of metal off the end of the pipe connector and several dents around the seal didn't make much difference. We ended up making the seal good by grinding down the end of the thermostat housing slightly... It seems to be holding for the time being.

We should have gotten some photographs because obviously, we could have shown what a mess the housing was in!

While our friends and my girlfriend played on the X Box, Kate her friend John and I continued to play, putting a new set of hoses on (KY jelly really helps the rubber over the pipe!

) and fixing the right sidelight/indicator (which had rusted completely and stopped working due to no earth)

A fun day had by all.. err... I think... though my GF now needs to be convinced now more than ever that Mogs are reliable...

Hebe and Rebecca finally meet up. Look at that shine!

We're doing WHAT?

Post by **Kevin** » Tue Jun 29, 2004 10:54 am

A couple of other points that can help always use copper grease on the studs to stop them seizing onto the housing and if the holes are really tight open them up a fraction so they go on easily or get a brass housing from Minor Developments.

Post by **Multiphonikks** » Sun Jul 04, 2004 12:09 pm

Damn...

Still boiling over, but at a much much slower rate.

The professional flushing of the system has been recomended. And the article in Minor Matters this month about radiator limescale sounds similar in places to my problems. The radiator doesn't leak: and we have new hoses. (Apart from the heater send and return hoses)

Is there anything I can put in the radiator (obvioulsy after I've got the pipes off) to flush it myself?

Cheers.

Nikki

Post by **Willie** » Sun Jul 04, 2004 4:37 pm

You can buy something like Radflush (made by Holts) or, as I
would do, buy some kettle descaler. block up the bottom rad
outlet and pour the descaler in then top up with water until you can just see the level is above the top of the internal fins. You should see
some bubbles as the stuff starts to disolve the blockages. I would leave
it in overnight and then drain it off. Hopefully you will see a lot of
muck emerge. Then REVERSE FLUSH the rad by wrapping cloth
around the hose pipe and inserting in the bottom outlet. I am
assuming that you can see water flow in the radiator top when the
thermostat has opened? i.e. the pump IS working!

Post by **salty_monk** » Sun Jul 04, 2004 6:07 pm

Bars flush seems to be pretty good & is the only one that you leave in for any length of time... mix it up, chuck it in & drive as normal for a couple of days.... worked for me (you should have seen the gunk that flushed out & ours wasn't overheating..)

Rad out - flush till clear, backflush till clear & keep going with the flushing some more.... then I'd renew your heater pipes just because you have the system empty & give it another go... If it doesn't work I reckon you need an exchange rad from Bull Motif or somewhere....

Post by **Multiphonikks** » Mon Jul 05, 2004 7:24 pm

Thanks for that

I'm going to give it a go next time I'm near anywhere I can buy the stuff.

And then wait

Out of interest, how does one backflush?

Cheers

Nikki

Post by **Willie** » Mon Jul 05, 2004 9:14 pm

Flushing of the rad is by inserting the hose in the top of the rad
and flowing water through. Backflush means to make the water
flow in the opposite direction. i.e. insert the hose in the bottom
pipe and flush so that the water comes out of the top. The same
proceedure is useful when flushing the heater matrix.

Post by **minor_hickup** » Thu Sep 08, 2005 12:37 pm

make sure to flush out the heater as well, but not with too much pressure.

Post by **Peetee** » Thu Sep 08, 2005 5:57 pm

BE WARNED!!
I used toilet cleaner on my engine and let it sit in the water channels for a while. I was ready to carefully flush out the stuff (making sure I didn't get water where it shouldn't as the engine was still in place) and was lucky enough to notice that the stuff had turned into a gel in places, effectively blocking some of the water channels. it was a devil of a job with a hose making sure all those were clear.

Post by **rayofleamington** » Thu Sep 08, 2005 10:42 pm

Bars Flush was the only one that seemed to do anything when I did some semi scientific tests (my previous volvo had long term overheating problems). I sat a crusty waterpump in a bucket and tried everything from Halfords and a few other things - most did nothing at all.
I ran it through in my Volvo and it made it better but it wasn't until a year later that I found a small steel pipe off the aluminium head that had blocked (really dumb idea- obviously it had furred up due to dissimilar metals) causing the head to air lock . Even after that was fixed it wasn't fully cured

Kettle descaler might be better but my local supermarket didn't have any so I never got to try it.

Post by **Blunt** » Thu Sep 08, 2005 11:19 pm

shine?

that's buff

Post by **MikeNash** » Fri Sep 09, 2005 5:12 pm

Re flushing, I saw that the stuff use in central heating systems has to cope with a range of metals some of which are in Morrises. So back in May I put in half a bottle of Purimachos "Flushex"and a month and 1500 miles later drained flushed and re-filled with the other half. Drained flushed a few weeks later. No leaks even though I depend on Radweld to keep it watertight. Heater now much hotter,even too hot! Am using a 88C thermo. Regards, MikeN.

Post by **chickenjohn** » Fri Sep 09, 2005 6:11 pm

I have to confess when faced with stuck thermostat housing I "removed " it with a cold chisel and club hammer. New ones are about £10 which I would rather pay than spend hours trying to get it off intact.

I also use Brita filtered water to top the rad up!

Post by **Handy** » Mon Oct 10, 2005 4:52 pm

The best descaler I have ever found,is Stop Bath which is used in photography to neutralise the developer.
Go to Jessops and buy a couple of bottles of their own stuff.Add it to boiling water from your kettle or mix it 75% water 25% stop bath and boil it up.It will almost instantly descale your kettle too

I then used Holts rad flush to do the engine and heater etc....
Two days later,I had to replace the original water pump as the sludge had been acting as a sealant

My thermostat housing was well stuck so and badly corroded so I replaced it and fitted an 88 degree thermostat from ESM.
I smeared the studs with copperslip to try to slow down the corrosion process.
Cheers,
Ian

Post by **Kevin** » Tue Jul 25, 2006 3:41 pm

A lot of the problems are caused because of the reaction between the alloy housing and the steel head and by not using a good 50% solution of antifreeze all year round, after flushing through its worth opening the holes up a fraction if they are tight on the studs and putting copper grease on the studs and this will eliminate most problems or you can get one of the brass housing`s from Minor Developments.

Post by **rayofleamington** » Wed Jul 26, 2006 12:36 pm

do thermostat housings stick more in areas where limescale water has been used (eg down south) than areas up here where we can keep kettles and washing machines for hundreds of years?

The aluminium oxidises clamping the housing to the steel studs.