How To: VR6 Thermostat Housing Replacment

[ReekieVR 0]

Same here. Cracks in coil pack. Had planned to use J B Weld, but cant find a non internet supplier. I can see you have one on the case too. Same place as mine.

 

Shame i didnt see your post sooner. I just ordered the sensor housing from VW yesterday.

 

Halfrauds sell JB Weld or at least they used to.

 

Seems they only sell the stuff in a bar, not the two tubes. They stopped stocking it. I think the Araldite reps have been working hard....

[Connorado 0]

Really great write up, wish i had found it a few days earlier tho.

 

just finished doing mine for the third time this week and i've still got a fecking leak... grrr!! there seems to be a small trickle of coolant running down the joint between the 'crack pipe' and the lower connector of the housing, there wasnt any leaks when i took it apart (thermostat was knackered) and all of the components all seem to be fine except for the lower connector (adjoining crack pipe), which has now been changed along with the seal and just to be sure i changed both seals on the crack pipe and the main seal that joins the cyl head but im still getting this leak.

 

Can anyone tell me whether it would be coming from the connection from the crack pipe or could it be running down from the main joint to the engine, the seal that i took off doesnt really look like the one i got from VW, the old one had a square profile and the new one is round (housing has a square groove and i cant image it makin a great seal), could i have a none OE thermo housing? i have included a pic of the seal below.

 

to make things really worse as well now the car doesnt seem to like starting when hot anymore, could this be an upset sensor?!

 

Am really at my wits end with it and could really do with some advice if you got any, cheers!

[ReekieVR 0]

too make things really worse as well now the car doesnt seem to like starting when hot anymore, could this be an upset sensor?!

 

Interestingly, one of the main reasons i am doing mine was to try and fix a hot start problem ! I was changing the rad switch and the blue and yellow engine sensors. As i was going to be draining the coolant anyway, i thought i may as well replace the stat, housing and cure a small leak down there. Now i am repairing the coilpack as well.

 

Hope this doesnt all grow into a multiheaded-niggle-monster.....

[Connorado 0]

So do you think it could be down to the blue and yellow sensors? what do these control and are they expensive to replace? also whats the black one for?

[mic_VR 3]

So do you think it could be down to the blue and yellow sensors? what do these control and are they expensive to replace? also whats the black one for?

 

Black is the instrument readout I think, blue one is the one that if knackered throws the ecu out and is worth changing. Have you checked for cracks in all the hoses? The rubber gets man handled a bit during the replacement of the housing and you could have a small split?

[Connorado 0]

yeah i've checked all the hoses and they all seem to be ok, any thoughts on the housing seal? does the one in the pic look right to you guys, the profile is totally different to one i put back in.

 

On the upside, engine is running much cooler now...... one step forward, two steps back!!!

[ReekieVR 0]

Just put all this back together and filled it up with coolant. But a leak !

 

I must have missed something during the re-assembly.

 

How does the long diagonal coolant pipe, which goes accross the fron of the engine, attach to the lower flange just below the senors? When i took it off i seem to remember it just pulled away, but i dont recall concentrating or checking that it was all in place before i did the housing bolts up. It looks snug as now, but thats where the coolant is pouring out ( havnt even started it yet !). Is there just a rubber o ring which the housing slides onto ?

[mic_VR 3]

Yep the crack pipe (long pipe across the front of the engine) should have a rubber O-ring that the thermostat housing seals onto when you push it all back together. It should be a pretty tight fit so if it was easy to push the two back together I'd check the condition of that seal.

[Connorado 0]

Sounds like the same thing thats happening to mine, i've just re-done it and it looked like it was actually leaking from the lower elbow (which connects to the crack pipe) where it bolts to the thermostat housing. i've used a load of silicon to seal it up, gonna leave it a few hours before filling up again but ill let you know if its done the trick.

[ReekieVR 0]

Ok, here are some details of what i did and the problems i encountered:

 

1stly the coil pack. After a cleanup it was obvious that although i had never had any problems with rough running in the damp, there was a potential problem lurking for the future. You can see the now legendary cracks appearing across several of the faces of the plastic.

 

 

So, after being unable to find the high temp epoxy i wanted ( JB Weld - if you are looking for it, just order it off the web and save yourself the hassle of finding out that real shops dont sell it anymore ! ), i went for some plastic-weld from maplin. This does not have a particularly hight temp rating ( 100 deg c )but i figured it would be close enough .

 

Anyway, you can see the repair below. I covered all 4 sides with the resin and any other faces with cracks appearing.

I will check the state of this epoxy after a couple of weeks and report back if it shows any signs of failure.

 

Next was the thermostat housing.

The old part looked in reasonable condition, but closer inspection revealed many issues ! ( I will post the pix i took shortly.)

 

My previous post about leaking coming from the crackpipe connection, was due to human error. I had removed the old seal and forgot to put a new one on ( :oops: ). However, after i bolted it all back together for a 2nd time, i found water seeping out from around the block / housing area this time. I was initially worried that i had tightned the bolts up too much and distorted the plastic, so experimented with various torque settings. They just seemed to move the leak around though.

 

Anyway, i had noted some nasting pitting on the block when i cleaned up the face and decided that this was the problem :

 

I found some old Chemical Metal in my tool box and filled in the holes. Once it had 1/2 cured i shaved off the excess with blade. After putting the housing back on, all leeks seemed to have stopped ( so far, touch wood etc ).

 

Hope this helps. I know that the prev how-to articles never made it to an actual wiki, but if anyone wants to stick my stuff in there, feel free.

[poll250 0]

Hmm I think mine is turning into some multi-headed fault monster at the moment. I replaced everything and filled it up with water/coolant mixture then found a leak coming from the yellow temperature sensor! When I put it in it was much looser than the other two but I thought with the seal in place it would still be ok, I guess its a faulty housing from VW then..... dangg.

 

Add to this the fact then when i tried to drain the remnants of the coolant earlier I ended up draining some oil! If someone could give a definite location of the drain plug I'd be forever grateful! I gotta drain all this new coolant mixture out to reuse!

 

As a further kick in the head, I cleaned the ISV while I was waiting for parts to arrive, maybe a little too much, as now when i start the car it just searches for a second or two, goes to 1500 revs then cuts out. I'm kinda hoping it could be an oil pressure related problem.

 

Argh the fun of Corrado ownership

 

Andy

[poll250 0]

Right quick update,

had all the housing off the car again, found the drain plug this time! Turns out that the yellow temp sensor ( now a shiny black and blue one) doesnt fit in its hole snuggley enough and leaks through the seal. Its noticeably easier to put the sensor in compared to the other two and you can wiggle it about!

Looks like an early morning trip to the dealers to get them to replace it; unless anyone has any suggestions for getting it to fit in there ? I guess all glues will melt by 100 deg so thats out...

 

Oh sorted the weird dead engine symptoms - tracked it down to water in the maf connector, no idea how that could of gotten in there, but its a big relief!

 

Andy

[steve @ 0]

Good news chap. Got mine back on the road today after breaking the drivers side door mech .. lol.

[poll250 0]

Mine should be back on the road this evening too! I can't wait! Who knows what lerks round the corner though: gonna try and fit some 312s and coilies in the next week or two..... Wish me luck!

 

Andy

[poll250 0]

UHOH! wellll There's no leaks!

The car idles fine and doesnt stall, BUT the third, super loud, fan seems to be permanently on. iI came on when the temp reading was about 70, and now, about 3 hours later, when i turn the key in the ignition it comes straight on, without evenstarting the car.

 

Before the whole leaking dealie started the temp gauge in the car was fine, and the fans were fine too I think. Although I think the other two fan settings may of stopped working just before the leaking got real serious.

 

I have replaced the Blue and yellow sensors, and gotten a neuspeed thermostat.

 

Any Ideas?

 

Oh I've also found this wire with nowhere to go? is it just an ambient temperature sensor?

 

[steve @ 0]

The loose wire is nothing to worry about Andy ... not sure what its for though lol.

[mic_VR 3]

Oh I've also found this wire with nowhere to go? is it just an ambient temperature sensor?

 

I've got the same wire loose on my C as well. No idea what it's for but it's never been connected to anything by the looks of it! :?

 

As for the fan problem, not really sure other than suggesting cleaning all the electrical connections (Fan, Senders etc) that might have had water splashed on it during the housing change. Then, and I know you're not going to want to hear this but......

 

Senders are:

 

Yellow 4 pin - Temp Gauge and aux water pump... which you've changed

Blue 2 pin - Engine Control... which you've changed

Black/Green 2 pin - 3 Stage fan....... which is the only one you haven't changed?.... :mad:

 

Sorry dude.

[flyferrari 0]

Looking in the Bentley manual it appears that the assembly that holds the thermostat itself is separate from the thermostat housing. Having had this lot apart yourself do you think it would be possible to change over a thermostat without removing the entire housing assemly first or am I dreaming!!!

 

Regards

 

Kevin

[ReekieVR 0]

I think you could if you got all the pipes etc out of the way 1st.If its an original housing though, it may not appreciate the extra stress of being messed with, plus even when the bolts are out, i think it was still a bast getting the thermo cover off. Just give it a shot, but be prepared for replacing more tha you bargained with !

[Jon_vr6 1]

im goning to have a crack at this next weekend a new thermostat has been put on and it still leaks from that area so to me it seems as if its the thermo housing! It doesnt leak while the engines running nor when i turn it off its about 1-2 hours later i look under the car and there is a very small puddle of pink coolant!! Are the part numbers around ?? And is it easy to distiguish what parts go into where seals, o-rings etc?? Just dont want to be pulling my hair out next weekend going where the hell does this go??

[Jon_vr6 1]

anyone??

[herisites 0]

Its really simple to do mate and the part is easy to get, just when you order the part make sure you say its the WHOLE thermostat housing not just the adapter on the end, mine fell apart the other day when chaging mine, went vw and ordered a new one and they only ordered the end bit that connects to the crack pipe. So tell them its the BIG bit that the upper and lower rad hoses connect to and you might as well get the bit that goes onto the crack pipe as well. It will come with all the O-rings you need and they are all self explanitory.

 

Its a LOT easier to do if you remove the front bumper/cross-member and rad (very easy just lots of bolts!) then just drain the coolant from the tap in the crack pipe and lower rad hose, removre the rad hoses from the stat housing and undo all the bolts (if it feels difficult to get off there may still be a bolt in it, one of them is hard to find!) then simply remove it, put the new o-rings, stat and plugs etc in place and then when you put it back together use lots of silicon sealant and it shouldnt leak at all then.

[Jon_vr6 1]

Cheers dude might just try the way on this thread as ive had the front end off before and its a pain in the arse lol! Silicon sealant ?? is that really needed ??

[herisites 0]

Cheers dude might just try the way on this thread as ive had the front end off before and its a pain in the arse lol! Silicon sealant ?? is that really needed ??

 

Yeah some kind of instant gasket/silicon sealant type stuff round where anything connects up that could leak will stop it leaking, better to be safe than sorry, last thing you want is to replace the housing and it leaks!

 

I personally think it will be a right PITA with the front end on, for the sake of a few bolts and sliding the bumper and cross member off its worth it imo as you can get right in there, but its up to you at the end of the day.

[Jon_vr6 1]

will see mate if i find it a pain in the arse with the front end on ill take it off!! Cheers for the help!