How to fix leaking thermostat housing on 200tdi ?

I've been searching for the source of a coolant leak on my 200tdi and I think I've tracked it down to the joint between the thermostat housing and the cylinder head. Does anyone know if it is possible to remove the thermostat housing without removing the timing belt cover first ?

Should be able to take it off without removing anything. I changed mine when I had the head off, Is it a right fit against it then? I canny remember off hand..

MarkC123 said:

I've been searching for the source of a coolant leak on my 200tdi and I think I've tracked it down to the joint between the thermostat housing and the cylinder head. Does anyone know if it is possible to remove the thermostat housing without removing the timing belt cover first ?

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yes bottom 2 bolts are on slotted holes so bolts only need loosening

Id change the bolts at the same time, there notorious for snapping.
I've prittey much replaced all bolts now with stainless Allen head bolts. Just the simple things that makes jobs so much easyer, example, fuel pump housing with the four silly flat head screws.. So much easyer with Allen head, all my thermostat housing now Allen head. Id say nearly all my suspension is with Allen bolts now..

MaxyMan said:

Id change the bolts at the same time, there notorious for snapping.
I've prittey much replaced all bolts now with stainless Allen head bolts. Just the simple things that makes jobs so much easyer, example, fuel pump housing with the four silly flat head screws.. So much easyer with Allen head, all my thermostat housing now Allen head. Is say nearly all my suspension is with Allen bolts now.

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i cant believe anyone would say that

Haha whys that James id like to hear your thoughts?

years of undoing nuts and bolts ,and the wider the head the better

jamesmartin said:

years of undoing nuts and bolts ,and the wider the head the better

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I fricking hate Allen bolts aswell, only useful on pushbikes

MaxyMan said:

Ok. I've found Allen head to work good for me anyway. Most of the offroad parts specialists that build or suply parts for comp trucks use Allen head on their shock mounts and relocation brackets etc etc. I've had no head or bolt shear as yet and prob not for many year to come, I understand what ya mean about wider head but everything gets a washer anyway so brings it up to the same size as a normal head if that's how you meant it?

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not quite ,an allen key has a small diameter for bolt size ,you can shear the head of a std bolt ut not an allen screw head or tool will fail first,they are used not for any practical reason unless head space is limited but to give appearance of a tech solution

flat said:

I fricking hate Allen bolts aswell, only useful on pushbikes

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Haha that's prob why I like them then!! Used to race XC (cross county) at national level in my slightly younger youth

jamesmartin said:

not quite ,an allen key has a small diameter for bolt size ,you can shear the head of a std bolt ut not an allen screw head or tool will fail first,they are used not for any practical reason unless head space is limited but to give appearance of a tech solution

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Oops deleted it james I understand what ya mean but specialists are suplying and using them and I've had no problems and just personally prefer them but I get what your saying!

A lot of the time these suspension components and mounts are limited to space so that would be one reasons why their using them.

I just find it easyer but everyone works differently..

Edit* a lot of modern cars are now using Allen head and torx, working on an XC90 other day and i have to say 90% of the suspension & braking is all Allen head. Same as Honda civic type R I've got that is mainly Allen head underneith

MaxyMan said:

Oops deleted it james I understand what ya mean but specialists are suplying and using them and I've had no problems and just personally prefer them but I get what your saying!

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a bolts a bolt subject to quality so allens no better than a std ,head type and so tool used to undo them is a different matter ,they are for restricted spaces but used for appearance ,its not a criticism if you like them just facts

You've got it spot on there I think fella! Need a good quality part (bolt) & a quality tool that fits well to begin with. Only start rounding heads of or snapping of bolts when your using cheap made parts or tools. Along with a good method can't forget that!

OK so for some people, Allen screws are fine replacemments for some stuff, which brings in the question of how do you set the torque without having to go out and buy a set of very expensive 3/8" or 1/2" drive Allen keys?

My set cost around £20 thirty years ago, and I think I've only used them less than a dozen times!!

Old man aquried about 1000 odd all different sizes with matching nylocs and non nyloc before he was made redundant at a well know steel & forklift company. RS components I think their boxed..

Thanks for the advice. I'll get a new gasket and have a go at fixing it

Don't be tempted to use any Gasket Goo-type stuff, use proper paper gaskets, and make sure that they are dry before you put them on.

The coolant then soaks in and swells the paper amking a water and pressure tight seal.

anyone know where to get the bottom half of the housing as mine has pulled the threads out of it when I changed my thermostat as I was just nipping the bolts up so now I have a pressurised leak that empties the coolant at a crazy rate. I realise I could helicoil the stripped threads but would prefer changing the unit to prevent any future problems