Thermostat Removal 84 1.9L

[Ahwahnee]

I seem to have a permanently open tstat. Trivial looking enough task but a search reveals a tendency for those 2 thin bolts to want to sieze and break.

The questions (having never held the tstat housing or water pump in my hand):

The longer bolt appears to be a thru bolt, i.e. I can see the other end of the bolt hole on the top of the tstat housing. Is the bolt closer to the engine (which appears to be shorter in the Bentley) also a thru bolt? I'm soaking the one I can see in PB Blaster, if the other bolt hole presents a similar open end I can start squirting blind where it should be (can't quite see it from above).

Are both of the bolts equally prone to seizure or is the long one more likely not to move? I assume the seizure is thru the length of the hole, possibly due in part to the dissimilar metals used?

Any advice, sympathy or what not most welcome.

[hdenter]

I have not had to do this yet, so I can't offer any advice. I just thought I would bump you back up to the top of the list so that someone else might see it and chime in. Good Luck!

Hans
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'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[seanjenn]

did my t-stat a couple years ago. either or both bolts can sieze/strip etc. soak 'em in pb blaster a day before doing the work.

then, ease them out, nice and slow. don't "break em loose" so to speak. gradually apply take off torque until they loosen. once you get the bolts out inspect the threads, wire brush bolts and chase threads if needed.
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1987 GL Sunroof
2.1 4 spd

[msinabottle]

When putting them back in, would just a dab of Anti-Seize be advisable? Or might that lead to trouble later?

Best!
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'Winston,' '84 1.9 WBX Westy
Vanagon Poet Laureate: "I have suffered in
many ways, but never, never, never in silence."

[Terry Kay]

After soaking them in Kroil, istead of just trying to crank them out all at once work them back & forth.

Turn in a hair first, then work them a little at a time out--not all at once.

You'll be less prone to snapping them off with the wiggle routine.
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T.K.

[camerahunter]

Mine came off with no soaking and no trouble at all. It never hurts to be careful though and the wiggle method is always best on the old cars as a previous member already mentioned.

Thank you,

David.
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1984 - Daily driver

[morymob]

A couple days before start streatching your fingers for re-assembly, about 8" should do it.

[ftp2leta]

First of all something is very unusual in this picture

Most of the time (van/engine condition) one won't come out.
It's not a rust problem but a coolant corrosion one.

Here is what I would do, coolant out! Replace water pump. This way you can remove the pump (easiest) and work on a bench to loosen the other screws.
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Working with rust, grease, dirt and dust is a sad truth.
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[CTB]

Both of mine snapped when I attempted to separate my t-stat housing from a failed water pump this summer, and I was trying to not "break them loose." Unfortunately, the combination of steel bolts, aluminum housings, and corrosion wasn't a good one. I admit I did not soak them; this might have helped, but mine looked pretty bad inside. Since my repair was much more extensive than just the t-stat, I ended up buying another housing. My old one is still not apart, but it could possibly be saved by drilling.

I *think* I anti-siezed the new ones, but honestly now I'm not sure. Good luck, and take your time.
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CTB

[Ahwahnee]

[Ahwahnee]

The bolts are out.

Thanks for the tips and encouragement to be patient. I soaked them for a couple of days... since they are soaking upside down I made little pans out of film container caps, cut a bit of towel to fit and held them against the bolt heads using rare earth magnets under the caps. Then I was able to dribble PBlaster into the cups from above to keep the towel wet and the bolt heads soaked for a day & a half (BTW, the towel bit was my wife's idea).

I recalled a story from a book a mechanic friend wrote about working on cars -- when he hired a novice he would have them clamp bolts of various sizes in a vise and then wrench them til they broke. He wanted them to get to know what it felt like when a bolt was twisting apart rather than turning. I did this with a few old grade 5 bolts of similar size to the ones in the thermostat. It was distressing how easily I could break them (about 12 lbs on the ones I tried using a torque wrench).

Thanks again -- I was really hoping to avoid (for now) an R&R of a perfectly fine H2O pump and the gyrations involved in getting that thing out & in.

[CTB]

Result! Excellent, glad that worked out for you. Nice thinking on the soaking bit.
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CTB

[chojinchef]

[mtwrench540]

i see that some has found kroil,best stuff i have ever used! one

[Ahwahnee]

Just a quick follow-up for future searchers as I found little out there about the tstat R&R on early (1.9L) engines and even the Bentley suggests it is difficult unless you remove the whole unit.

Was straight forward though the install was much easier with the oil filter removed -- then you have enough room to get a hand on the lower housing body whilst fitting up the bolts. Was not even necessary to bleed the coolant as I was able to get all I caught back in there with the overflow just a bit higher than before. A couple of drives and it self-bled that bit.