Thermostat housing bolts size needed

Tiny
LILMANSDAD
  • MEMBER
  • 2004 CHRYSLER PT CRUISER
  • 2.4L
  • 4 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 250,000 MILES
Lost the bolts that hold my thermostat housing in and can't find a clear answer on what size they are.
Friday, April 22nd, 2022 AT 12:15 PM

3 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,864 POSTS
Part number is 06104364AA. You are correct. Finding the size is just about impossible.

Easiest is to just find them in a salvage yard. Besides getting the correct size, if the holes are drilled into the coolant passage, the bolts will be specially treated for corrosion resistance. Standard bolts can cause "galvanic action", (corrosion), when two dissimilar metals come in contact with an acid. Acids normally develop in engine coolant over time. Antifreeze has numerous additives, one of which is a corrosion inhibitor, but those additives wear out in about two years. If the cooling system is neglected, those two or three bolts could become stuck and break off next time they need to be removed.

You will also usually find a stepped shoulder under the head of the bolt. Its purpose is to center the thermostat housing over the hole in the cylinder head or intake manifold. Regular bolts won't do that, possibly resulting in the rubber seal being pinched under the housing. The housing won't sit flat, the seal will leak, and the ears on the housing could break if the bolts are overt tightened.

Torque spec is 20 foot-pounds for these bolts.
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Friday, April 22nd, 2022 AT 1:05 PM
Tiny
TODDANDDEB2001
  • MEMBER
  • 1 POST
Torque specs on thermostat housing bolts for pt cruiser is only 8.75 ft lbs.
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Monday, October 7th, 2024 AT 10:51 AM
Tiny
CARADIODOC
  • MECHANIC
  • 33,864 POSTS
Thank you for the correction. 20 foot pounds for such small bolts does seem too high, but that's what they show in the specs list. If you look at the drawing I posted previously, there they list only 110 inch-pounds, which makes more sense. That comes out to just over 9 foot-pounds. Your correction will likely save some people some trouble.
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Monday, October 7th, 2024 AT 3:05 PM

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