36 replies to this topic

[Paintmonkey]

Don't think it's an airlock. Had engine running with heater valve in open. With new thermostat in place there was no flow of water through the radiator, with the thermostat removed water gurgles quite happily through the rad.
The mini garage did mention drilling holes in the thermostat, but since everything worked with the old thermostat I don't see why I should need to do this. Surely having holes drilled into the thermostat is pretty much the same as running without a thermostat which is what I'm doing at the moment!
Oh yeah, the thermostat was definately put in the right way round!!!
What I need from you guys (& gals!!) is your opinion on whether it's the head gasket or not. Last weekend after I'd removed the thermostat and before anyone mentioned head gaskets, I drove it for about 40 miles, doing upto 80mph, engine ran smoothly, temperature guage sat at 'normal', no probs whatsoever!! Now if it was the head gasket would the car have done this?
Don't want to risk damaging the engine if it is the head gasket, but don't want to waste the time & effort changing the head gasket if you lot think I've been supplied dodgy thermostats!!
If it helps anyone, the thermostats that the mini garage have been supplying me are made by a company called 'FIRST LINE', part No. FTK003 (thermostat kit - Audi, Ford, Nissan) --no mention of minis there!! The thermostats themselves are stamped on the bottom 88C 192F.

Cheers
Rich

[alicetheauto]

Clutching at straws here, but is it worth trying a thermostat from another source? In case the supplier has a dodgy batch.

[Paintmonkey]

Clutching at straws here, but is it worth trying a thermostat from another source? In case the supplier has a dodgy batch.

Haven't had chance to get one from anywhere else yet.
Going to the Mini show at Himley Hall this weekend, hopefully in the estate. It's about a 40 mile round trip.
I won't get chance to change head gasket before then, so wanted to know what everyone thought!
Was going to get a couple of different thermostats while I was there.

[racingbrett]

if the problem only started happening straight after the stat was replaced i would find it a bit unlikely to be the head, theres usually other signs associated with head gasket failure aswell...

water in the oil (look under the rocker cover for water droplets on top of oil, check for mayonnaise like stuff on the oil fil cap or under the rocker cover)
loss off power.

a quick compression check will be the easiest way to tell for sure.

stats, not a sure way to test them but ill normally take them put them in a pan and pour a fresh boiled kettle of water over them it should open (last one i checked i threw into a pan of water on the hob just to check for sure, it only opened when the water was on a violent boil and it only opened 3 or 4 mm).

is the pipe definatly filling with hot water and not steam, give it a squeeze see if you can feel water flowing through.

possible water pump problem?


**edit** just a thought water pumps dont always just stop dead, they can slowly loose there pumping capacity/pressure, when you remove the stat you are also removing a restriction so the pump doesnt have to push as hard. Is there any chance u used rad weld or similiar recently?

air locks can be a mother of a problem but "usually" form at the highest point i usually slacken of a pipe at the highest point i can find n while wearing some thick rubber gloves give it a wiggle see if its air or water coming out (be real carefull here the waters hot)

Edited by racingbrett, 06 May 2009 - 09:39 AM.

[Paintmonkey]

Ok thanks for all those ideas! I'll answer each one to see if it throws any more light on the problem!!
-There is no mayo junk on oil filler cap. In fact the inside of the rocker cover looks spotless
-I haven't noticed any loss of power. As I said last weekend did about 40 miles, car behaved itself, engine ran well and easily kept up with the flow of motorway traffic
-All pipes seem to have water going through them with the thermostat removed
-Disconnected the top rad hose and there is water coming through it. Alos I've done about 50 miles since deciding to remove the thermostat---would any possible air lock have freed itself in that time? Water level hasn't changed.
-Just tested the two 'new' thermostats....Both failed to open in water from a freshly boiled kettle! Stuck them both in saucepan!! One opened a fair distance, the other only about 2 or 3mm but the water was boiling violently!
-The water pump shows no signs of leaks, no strange noises coming from it and the fan works as it should do!
-Is it possible to do a 'homemade' compression test? Don't really want to take it to the garage since they've already decided its the head gasket!

Like you I find it strange that the problem has only arisen since I changed the thermostat. Could be a coincidence or more likely just murphy's law that it's the head gasket.
Thanks for the ideas
Rich

[998dave]

Has the engine got a bypass hose? If not you'll need to drill these holes.
Did the old thermostat have these holes, (unfortunately you've thrown it away so can't check.

What temperature thermostats are they, may look the same, but have standard temperatures, sounds like they've very hot, I think 82 or 88 degrees are normal in mini's, you should use a thermometer to monitor water temp when checking.

Dave

[Grayedout]

Also don't be tempted to run for too long without a thermostat as this can cause problems in itself. If you need to run without one then you need to fit a blanking sleeve available from Minispares etc !

[Paintmonkey]

Has the engine got a bypass hose? If not you'll need to drill these holes.
Did the old thermostat have these holes, (unfortunately you've thrown it away so can't check.

What temperature thermostats are they, may look the same, but have standard temperatures, sounds like they've very hot, I think 82 or 88 degrees are normal in mini's, you should use a thermometer to monitor water temp when checking.

Dave

Engine is from a 1993 mini rio with a bypass hose. As far as I can remember the old thermostat didn't have holes drilled through it.
The two new thermostats are stamped 88C 192F on the bottom, but to get them to open the water in the pan was nearly boiling over!
Unfortunately I don't have a thermometer!

[Paintmonkey]

Also don't be tempted to run for too long without a thermostat as this can cause problems in itself. If you need to run without one then you need to fit a blanking sleeve available from Minispares etc !

Apart from the engine taking longer to warm up what other probs would I be looking at?
Never heard of a blanking sleeve!! Just off to their website to have a look!

[cambiker71]

Also don't be tempted to run for too long without a thermostat as this can cause problems in itself. If you need to run without one then you need to fit a blanking sleeve available from Minispares etc !

Apart from the engine taking longer to warm up what other probs would I be looking at?
Never heard of a blanking sleeve!! Just off to their website to have a look!

Without a thermostat no.3 and 4 cylinders will overheat and it won't show on the temp guage, as the water will be pumped around the radiator and straight back past the water pump no.s 1 and 2 cylinders and temp guage sender unit which will only show the cold water not the boiling other end of the engine.

[Paintmonkey]

Also don't be tempted to run for too long without a thermostat as this can cause problems in itself. If you need to run without one then you need to fit a blanking sleeve available from Minispares etc !

Apart from the engine taking longer to warm up what other probs would I be looking at?
Never heard of a blanking sleeve!! Just off to their website to have a look!

Without a thermostat no.3 and 4 cylinders will overheat and it won't show on the temp guage, as the water will be pumped around the radiator and straight back past the water pump no.s 1 and 2 cylinders and temp guage sender unit which will only show the cold water not the boiling other end of the engine.

Yeah, sounds nasty!
Just had a look at the Mini Spares website, they say pretty much the same thing!
As well as fitting the blanking sleeve they also say to block off the bypass hose. If I'm gonna do that I may as well fit a new pump and just block the by pass from the head (at least it'd be one less place it could leak from!).
Still need to know if you think it's more likely thermostat prob or head gasket.
Rich

[998dave]

Has the engine got a bypass hose? If not you'll need to drill these holes.
Did the old thermostat have these holes, (unfortunately you've thrown it away so can't check.

What temperature thermostats are they, may look the same, but have standard temperatures, sounds like they've very hot, I think 82 or 88 degrees are normal in mini's, you should use a thermometer to monitor water temp when checking.

Dave

Engine is from a 1993 mini rio with a bypass hose. As far as I can remember the old thermostat didn't have holes drilled through it.
The two new thermostats are stamped 88C 192F on the bottom, but to get them to open the water in the pan was nearly boiling over!
Unfortunately I don't have a thermometer!

That'll be an 88 degree thermostat then, remember water doesn't boil at 100deg, it becomes steam at 100deg, if the contents of the pan we're all at 100degrees it'd all be steam and empty, so this temperature seems about right.

You may be looking at head gasket after all, a compression test would be the best way to get an initial check, and really doesn't take long, you can buy a tester for £20-30 I think.

Dave

[Paintmonkey]

Cheers
Think I might gamble on using it for the 40 mile round trip to Himley on Sunday, then as soon as I get chance give it an overhaul.
New head gasket, pump, by pass hose, thermostat (again! just in case!)
See where I go from there!

[jaydee]

long period running without thermostat will cause you head gasket failure.
Why dont you just eplace ur thermostat with another one and see how is it going? I dont think you have blown head gasket if drove the car 40 miles without any issue, no white fumes and no water in oil.

[Paintmonkey]

Already put two 'new' thermostats in.
Plan was to drive to Himley, without thermostat in, pick up a couple from a different manufacturer.
Fit them, see what happens. If the same thing happens then I guess I've gonna have to accept that it's the head gasket and go for that overhaul.
I was just hoping one of you wise lot would have had a similar problem and could have told me what it was!!
Car seems to run as well as it ever has done now the thermostat is out!
Just keep thinking that the car wouldn't run so well if the head gasket was blown....and then theres the other thought that this problem only happened when I fitted the engine steady and replaced the thermostat!!
Gonna have to start sticking to the 'If ain't broke, don't fix it!' school of thought!!
Rich