Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Big_Roger on 06 January 2008, 20:55:32
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Some information for anyone contemplating renewing the thermostat on their 3.2 L To save them the problem I have had.
The replacement VX thermostat 90502201 now being supplied has a thinner flange than the original. As it has no stiffener ribs it is at least 10 MM thinner. This means that the fixing bolts are then this amount too long, and as the rear bolt screws into a blind tapped hole in the crankcase it bottoms before the thermostat is tightened down enough.
Also, another bit of bad news, if your engine uses the Cambelt kit 93172354 (Where the top roller is more to the right near cam 3) then you cannot change the thermostat without removing the cambelt and tensioner assembly first.
There just isn't the room to get it out from above, as the tensioner assembly intrudes into the space in the vee very close to the thermostat. It has to come out through the space in the rear belt guard when the tensioner roller bracket is off. That is unless you are prepared to take off all the lower inlet manifold and bridge and fuel injector assembly to get at it.
A salutory lesson. I changed the thermostat when doing a cambelt & water pump change etc, no problems other than the usual transfer pipe bolt access.
When the whole job was finished and refilling with anti freeze / water I had water coming out somewhere at the front of the engine. My first thought was that despite the great care I had taken to make sure the seal ring remained in place when fitting the thermostat, it must have moved and was damaged. I removed the top of the inlet manifold etc and yes water was P**ing all round the thermostat housing. I set to removing it. thats when I found you can't get it out, so in the end I had to remove all the stuff I had put back to remove the cam belt and tensioners etc.
This is when I was really sick, there was nothing wrong with the seal ring, it was still nicely in place in the groove undamaged.
This is when I twigged that the housing was not tightening down because the rear bolt, although tight, wasn't going in far enough, the front bolt hole is a through tapped hole so wasn't a problem, This is when I checked to see the difference in the thermostats!!!
I have shortened the bolts and put thermostat back, and checked for leaks, all OK now.
Now I have to re do all my work again, back where I started Saturday morning.
Hope this helps someone
Roger
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Sounds like you had an interesting weekend, Roger, but managed to get through it OK with some thought and perseverance.
Will leave this thread for others to comment meantime pending moving to the maintenance/howtoo type area. Did you take any pics, perchance? Would make a good howtoo..... :y
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Hi
Afraid not, taking pictures was the last thing on my mind at the time !!
Would be pleased if it went in the How to sectin to help any one though.
Roger
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I can't say I've ever come across this issue before, but I've never done a stat on a 3.2, only 2.5 and 3.0.
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Interesting, I found the opposite.
The later stat I got had a thicker flange meaning it needed longer bolts, the original stat was thin.
I wonder if your dealer had old stock, or did you buy it on line?
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Is this likely to apply to 2.6 engined omega's as well?
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The important thing is that you got the car going... and thanks for the warning about different bolt sizes.
On another note, Removing the plenum, intake manifold, and lower bridge seem to me more straightforward then re-doing the cambelt timing....?