Overheats with thermostat in.

Any ideas why my 200tdi 90 over heats with the thermostat in. Since putting the 200tdi engine in I have nothing but trouble with the cooling system. I changed the radiator and the heater matrix went so it's had a new one of them. Bottom and top hoses are new too. It's blown off two radiator caps recently since I fitted a new thermostat. The old stat was broken and was slightly open. The new works as I tested it in a pan of hot water. With the stat out I can see the coolant move when I squeeze both the top and bottom hose so it has an open circuit and I'm presuming there is no blockage anywhere.

When the stat is in the bottom hose is cold and when it's out it just gets up to the white on the guage and all pipes are luke warm. The heating works when it's hot.

Cheers, Stu

is there summat physically stopping the stat opening?

The Mad Hat Man said:

is there summat physically stopping the stat opening?

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Ooh, don't know but I'll check it. I don't know what I'll be looking for though After putting the new stat in I drove about 5 miles to the supermarket and it sat bang half way on the temp guage and it warmed up really quickly. Coming back, it soon got up to half way be kept going so I thing the stat worked once

is the stat fitted the right way around?

ratty said:

is the stat fitted the right way around?

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I've got it in with the spring pointing down. I think it's got top stamped into it.

Is the cooling system setup with the right heights, i.e. header tank highest part of system?

discomania said:

Is the cooling system setup with the right heights, i.e. header tank highest part of system?

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I'll check it as I have changed the heater matrix. Luke warm water is getting around the system with the stat out.

Head gasket problems usually are ok with the thermostat out, in fact it's common to do such a thing when selling. Blowing caps off sounds like head gasket and probably why your matrix died as well.

You sound as if you are getting circulation but no harm in making sure the impellor of the pump aint loose.

The 200tdi has bypass pipes from the thermostat with a valve in it, also worth checking.

Have you tried running it up to temp with the cap off and stat in watching for circulation and excessive gassing, does the header tank smell gassey?

These engines don't run hot, so make sure the radiator is not a bit blocked up, get a hose fill it up and pull off the bottom hose and see how it empties. Was the coolant rusty?, also when running it up to temp run your hand over the radiator looking for cold spots indicating blocked bits.

david451 said:

Head gasket problems usually are ok with the thermostat out, in fact it's common to do such a thing when selling. Blowing caps off sounds like head gasket and probably why your matrix died as well.

You sound as if you are getting circulation but no harm in making sure the impellor of the pump aint loose.

The 200tdi has bypass pipes from the thermostat with a valve in it, also worth checking.

Have you tried running it up to temp with the cap off and stat in watching for circulation and excessive gassing, does the header tank smell gassey?

These engines don't run hot, so make sure the radiator is not a bit blocked up, get a hose fill it up and pull off the bottom hose and see how it empties. Was the coolant rusty?, also when running it up to temp run your hand over the radiator looking for cold spots indicating blocked bits.

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Water pump and radiator are new as the last radiator was blocked (or so I thought). The water was very rusty in the old rad and there is still evidence of brown in the current coolant. When I topped it up today the water seemed to fizz when I topped the header tank up which would fit with your gassy observation!

If the water is brown it could also be the head gasket - a lot of coolants have a chemical in them that makes them turn brown when they are mixed with combustion gasses - and they then smell funny too.

I've spoken to the guy who fitted the 200tdi engine and he's said there would be evidence if the head gasket had gone ie. White smoke, not starting or emulsified oil. None of this is present. I can't get it over 72mph and he seems to think the engine is holding back a bit if this tidbit is of any use.

He's a mechanic and a Land Rover enthusiast so he does know what he's talking about but he still hasn't got it sorted yet

I had a head problem (Warped) recently on a 300tdi and there was no evidence other than pressurising the coolant.
I ran it for a few months after my water pump died and had no real problem, then it started to get a bit hot and the heater started blowing cold.....along with increased pressure in the header.
I took the stat out and it was ok, pressure reduced slightly and no overheating.
I asked the question on here and was a bit skeptical as there was no other evidence i.e. emulsified oil, but it was the head, so don't right it off as a possibility.

I've just done the headgasket on my TD5. I too was sceptical about the gasket being blown. No oil or water contamination and only the coolant being pressurised at speeds greater than 50mph. I could leave it ticking over all day, I could drive it at 50mph all day. I did over 3000 miles like this with the problem occasionaly rearing its head. It didn't show up on either a sniff test or compression test.

Ratty did you have any major probs with your TD5 head gasket job?
Got to do mine when I fit my new head so an early heads up is always useful.
My head is leaking fuel into the oil but no other problems.
Can go about 2000 miles before I need to drain 12 litres from the sump.
So long as I dont go above 2000 rpm there does not seen to be any problem with the engine but above 2000 rpm the turbo starts to blow blue smoke. I'm hoping it is bacause of the diluted oil and not another turbo on its way out.
Sorry for the hijack.

Shifty1962 said:

Ratty did you have any major probs with your TD5 head gasket job?
Got to do mine when I fit my new head so an early heads up is always useful.
My head is leaking fuel into the oil but no other problems.
Can go about 2000 miles before I need to drain 12 litres from the sump.
So long as I dont go above 2000 rpm there does not seen to be any problem with the engine but above 2000 rpm the turbo starts to blow blue smoke. I'm hoping it is bacause of the diluted oil and not another turbo on its way out.
Sorry for the hijack.

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No. There were no unforseen problems with the headgasket itself. I decided to do the EGR blanking while there was plenty of room in the engine bay. The egr was fairly clean but a stud snapped and needed drilling out. Unfortunately the previous overheating blew the fuel cooler which meant that after getting the Head gasket done I was still pumping diesel into my header tank. I turned the engine off while waiting for some cattle to get out my way and could hear the expansion tank hissing. I **** a brick thinking the problem wasn't cured and that the injector rail could've been cracked. Have just fitted another fuel cooler and fingers crossed all seemed ok.

Although the HG had been changed before nylon dowels had still been used. I am now on the 3 hole gasket so fingers crossed I don't get it blow again.

When you remove the head, if you see black rings around the face of the head where the cylinders are then the chances are your head is shifting rather than the gasket being properly blown. This was the case with me.

ratty said:

No. There were no unforseen problems with the headgasket itself. I decided to do the EGR blanking while there was plenty of room in the engine bay. The egr was fairly clean but a stud snapped and needed drilling out. Unfortunately the previous overheating blew the fuel cooler which meant that after getting the Head gasket done I was still pumping diesel into my header tank. I turned the engine off while waiting for some cattle to get out my way and could hear the expansion tank hissing. I **** a brick thinking the problem wasn't cured and that the injector rail could've been cracked. Have just fitted another fuel cooler and fingers crossed all seemed ok.

Although the HG had been changed before nylon dowels had still been used. I am now on the 3 hole gasket so fingers crossed I don't get it blow again.

When you remove the head, if you see black rings around the face of the head where the cylinders are then the chances are your head is shifting rather than the gasket being properly blown. This was the case with me.

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Cheers for that. I've got all the tools but just not worked on the TD5 before.
Did you use new head bolts or just reuse the old'uns???

My fuel rail has definitely gone as I've changed everything else where fuel could leak into the oil and its still happening. I was trying to think of some way tp pressurise the fuel rail to confirm a leak before spending my hard earned on a new head. My motor had high oil levels when I bought it so God only knows how long the problem has been present.
Luckily no fuel in the header so far and no overheating since I replaced the rad.

Shifty1962 said:

Cheers for that. I've got all the tools but just not worked on the TD5 before.
Did you use new head bolts or just reuse the old'uns???

My fuel rail has definitely gone as I've changed everything else where fuel could leak into the oil and its still happening. I was trying to think of some way tp pressurise the fuel rail to confirm a leak before spending my hard earned on a new head. My motor had high oil levels when I bought it so God only knows how long the problem has been present.
Luckily no fuel in the header so far and no overheating since I replaced the rad.

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I had new head bolts fitted. I didn't want the problem coming back especially as I intend to chip it and uprate the intercooler when I get some cash up together. The local engineer who was skimming and pressure testing the head wanted £500 all in to do the job for me. At that price I couldn't say No. It saves future arguements if the problem should re-occur plus I was short on time.

start the engine from cold run it for a few mins and squeeze the top hose, if it feels hard or pressurised then its a sure bet the head gasket has gone causing your engine to over heat.

vivnap said:

start the engine from cold run it for a few mins and squeeze the top hose, if it feels hard or pressurised then its a sure bet the head gasket has gone causing your engine to over heat.

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It's been blowing caps off so probably goes up like a balloon, in relation to other symptoms you mention, the compression is greater than water pressure therfore nearly always pressurises the coolant system, once it gets real bad then water can leak back into the cylinders and burn off or worse still cause it to hydraulic and bend a rod, to emulsify the oil once again it has to be leaking badly and at the right place and have time to emulsify. Normally all that will be present is a few droplets on the dipstick, but you will know how much water it is using.

In relation to loss of power, probably find it's blowing across two cylinders.

you dont always get the water and oil mixing . it depends if the oil and water part of the gaskit has blown, it could be the water and cylinder part has blown so pressurising the water system but being as there is no oil getting into the water it would not emulsify.