Coolant flange leaking dont know how to fix
- Thread starter slybunda
- Start date
The early production units of the 90's BMW M42 four-cylinder engines were built with a defective gasket sealing a coolant passage between the block and the head in the front timing case.
After about 40-60k miles, depending on how well the coolant was maintained, the gasket's failure would manifest itself via an external leak.
An improved gasket was the prescribed fix, but BMW noted in its service bulletin that if surface pitting had occurred, to use JB Weld to repair the surfaces.
Permatex 85420 is their equivalent to Hylomar Blue, but if you can get your hands on the real thing, that's the better option.
Hylomar can be used as a gasket dressing, or replacement, but given the fact that there is a groove for the o-ring in the other fitting, I'd keep the o-ring. I'm not a fan of relying on goop to bridge large gaps.
After about 40-60k miles, depending on how well the coolant was maintained, the gasket's failure would manifest itself via an external leak.
An improved gasket was the prescribed fix, but BMW noted in its service bulletin that if surface pitting had occurred, to use JB Weld to repair the surfaces.
Permatex 85420 is their equivalent to Hylomar Blue, but if you can get your hands on the real thing, that's the better option.
Hylomar can be used as a gasket dressing, or replacement, but given the fact that there is a groove for the o-ring in the other fitting, I'd keep the o-ring. I'm not a fan of relying on goop to bridge large gaps.
If it were me I would use RTV and forego the o-ring. Many applications, like the water pump on my Camry, have a "channel" for the RTV to go in, so it should work in the o-ring slot. But you probably want to get a new flange.
Originally Posted by slybunda
Good to know about paper gasket.
With this hylomar instant gasket stuff do i keep the original o ring in place and smear some instant gasket over it or does it replace the oring itself?
I would 100% fill pitting that deep with JB weld, you can also use Steel stick 8267 from JB on aluminum that cures in a short time and is firmer so it doesn't run. Coat both sides of the O ring and flange with the Hylomar, it will never leak again.
https://www.amazon.co.uk/Weld-8267-SteelStik-Reinforced-Stick-2/dp/B00RN7CT2U
Good to know about paper gasket.
With this hylomar instant gasket stuff do i keep the original o ring in place and smear some instant gasket over it or does it replace the oring itself?
I would 100% fill pitting that deep with JB weld, you can also use Steel stick 8267 from JB on aluminum that cures in a short time and is firmer so it doesn't run. Coat both sides of the O ring and flange with the Hylomar, it will never leak again.
https://www.amazon.co.uk/Weld-8267-SteelStik-Reinforced-Stick-2/dp/B00RN7CT2U
Originally Posted by Colvin
Find a welder that dose aluminum welding, he should be able to fill it then smooth it down. That's really the only permanent fix.
JB Weld like Trav said. When cured it will be a permanent fix. That stuff is amazing when used correctly.
Find a welder that dose aluminum welding, he should be able to fill it then smooth it down. That's really the only permanent fix.
JB Weld like Trav said. When cured it will be a permanent fix. That stuff is amazing when used correctly.
its all working working now. new flange is fitted and coolant is bled and fan kicks in as normal. used the red high temp gasket maker stuff and put it on the oring of the sensors too since i reused the old sensors and there was some corrosion around the them.
will keep an eye on it over the next few weeks.
will keep an eye on it over the next few weeks.
