Thermostat Housings and Sheared Bolts!!!!!!!

Adam · Post by **Adam** » Sat Aug 12, 2006 4:53 pm

I have the problem of sheared bolts, I can get the old parts out but seem to be drawing a blank for the replacements. My local hardware store says they're M7 but they can't get them in the length I need, my insider in Delphi (Lucas) can't get them either, he says that they are non-standard.

Will I cause any problems if I drill and tap the holes to M8?

AndersDK · Post by **AndersDK** » Sat Aug 12, 2006 5:03 pm

Yep -

M7x1 thread. Not standard in ole imp Britain

If there is enough materiel left when drilled & tapped to M8 - I dont see why you dont do this ?
Use alupaste (not copper-paste) when re-assembling. makes sure you can replace the thermostat again in 10 years not shearing the bolts

Kitch · Post by **Kitch** » Sat Aug 12, 2006 6:07 pm

I had this problem on the 16v.

Drilled the hole clean through, got some longer bolts then stuck a nut on the back of each bolt.

Its been fine since.

Brian · Post by **Brian** » Sat Aug 12, 2006 7:14 pm

Yep, that's what I have done several times now, no problems either, and just use silicon sealant and no gasket.

But clean off all the old gasket and rub the interfaces on a piece of flat glass, with either oil and carburundum paste or fine wet and dry paper soaked in thin oil or diesel, till all the faces are matt..

Good luck

Adam · Post by **Adam** » Sun Aug 13, 2006 12:00 am

Ok thanks chaps, my job list for sunday.

1. Change offside front and rear discs and pads.
2. Thermostat.
3. Cam belt and water pump.
4. Oil and filter.

Busy day, then the oil and filter and brake pads on the TGD, then the heater controls... oh yeah and the heater fan problem in the TZD. Early start I feel.

All is going well and I have resisted bashing things with big hammers so far!!!!

jeremy · Post by **jeremy** » Sun Aug 13, 2006 8:28 am

Had the broken bolt problem on my TD - fun getting the old ones out - then used nuts on the back. Don't seem to remember any thread problems but someone may have been there before me?

I cleaned it off well and used Hylomar to hold the gasket in place on the advice of my local accesory shopkeeper. If I was doing it again I'd do it dry - as I can't see why this joint should need any sealant apart from a new gasket.

Adam · Post by **Adam** » Sun Aug 13, 2006 5:38 pm

Bleed screw has now also sheared

I'm 99% sure my problems will solved when I get the blasted thermostat changed, fan's aren't kicking in but have tested and they do work and i've changed the rad switch, i'm also getting alot of pressure in the system, would a sticking thermostat cause this? Ran out of time today so i'm TZDless till next weekend.

Ian_Fearn · Post by **Ian_Fearn** » Sun Aug 13, 2006 8:59 pm

What sort of M7's do you need? What length??

2CV's are made with M7's so i'm bound to have the ones you need.

Adam · Post by **Adam** » Sun Aug 13, 2006 9:19 pm

I'm not sure off the top of my head and the car and bits is elsewhere at the moment. I'm gonna drill and tap to M8's for ease in the future, thankyou anyway. I'm more concerned with the bleeding caphead on top which is hollowed and crossdrilled, although my mate at delphi is gonna knock one up for me if needs be. I'm hoping it is the thermostat, how often are new fan switches faulty?

AndersDK · Post by **AndersDK** » Sun Aug 13, 2006 11:09 pm

Try jam a tiny screwdriver or hex key down the remainings of the bleedscrew and wind it up. My own experience is that they rarely is stuck once the head has sheared.
Any standard Allen head M5 bolt would do as replacement. But must be winded off fully to bleed then.

Adam · Post by **Adam** » Sun Aug 13, 2006 11:12 pm

Ok, thanks, i'll replace it with a standard one for now and get a proper one when i'm next at the scrappies.

Post by **docchevron** » Mon Aug 14, 2006 12:16 am

Adam wrote:Ok thanks chaps, my job list for sunday.

1. Change offside front and rear discs and pads.

Er, not trying to be arguementitive but only changing one disc????

Maybe I go over board but anything steering, suspension or brake related I ALWAYS do both sides.
But then, my cars spend more time in bits than on the road!!!!

Cheers
Chris G

Way2go · Post by **Way2go** » Mon Aug 14, 2006 2:20 am

docchevron1472 wrote:
Adam wrote:Ok thanks chaps, my job list for sunday.

1. Change offside front and rear discs and pads.
Er, not trying to be arguementitive but only changing one disc????

Chris G

2 years ago for the MOT I was running out of time for the retest when one of the items failed was the offside front disc. Took it back before doing the nearside as that wasn't on report and they failed it on nearside this time as brakes measured 35% out of balance.

(Got some xtra time to finish the job and it sailed through.)

Vanny · Post by **Vanny** » Mon Aug 14, 2006 6:28 pm

glad to see that everyone has done this at one time or other! I snapped a head off a bolt on the 19rd thermo housing and simply glued the thermohousing back down with instant gasket. The other two bolts held it down firm enough that it didnt leak again!

Drilling the whole thing out sounds liek a realy good plan though!

tom · Post by **tom** » Mon Aug 14, 2006 6:36 pm

Change both disks for heaven's sake! If your fans are not coming on, you could have a blocked radiator, poorly bled system or an electrical fault. It is rarely the thermostat alone that causes trouble. More often, it cannot work properly because the radiator is not circulating. Try shorting pins on the fan switch connector with a wire link to see if they come in. You won't do any harm.