Radiator replacement? Or teflon on petcock threads?

Post by **theWIFES_S70** » 20 Jan 2017, 22:37

Hey everyone, I broke the petcock flushing the system on our S70 about fifteen months ago. I've finally purchased an air shield (I know, I know...) and I went to eyeball it and noticed that my aftermarket petcock is weeping. It's not the original one as that one broke and I had to fish it out... and install one from my my 99 Altima.

I'm not losing that much coolant. Just drops here and there. I've tried tightening it down. But the little rubber gasket is already plenty compressed and I'm worried about cracking it... I'm thinking I might've ruined the threads when I had to remove the broken petcock and maybe I've been weeping all this time? I'm thinking it's time to replace it. The weather has been rather warm in NYC and I'm thinking if it continues, I might be able to get this done pretty easily. Of course, this means I can finally install the Volvo Temperature sensor I purchased a while ago (I've been on an FAE for over 12 months now!) and purchase a new coolant level sensor too (don't know how old that one is...) What do you all think?

Do you think I might be able to stop the leak if I wrapped teflon tape around the plastic threads of the petcock and rethreaded it? I know I'd have to be careful as teflon tape in the coolant system would probably not be a good move... Or with these plastic things it's better just to replace it and be done with it? As always, many thanks for the collective insight!

Post by **EstVolvo** » 20 Jan 2017, 23:19

I just replaced a radiator on my 2000 v70.
The Radiator had 150000 miles on it.
Plastic end cracked wide open.
Supposedly all the radiators fail around this mileage/age.

Post by **MadeInJapan** » 20 Jan 2017, 23:39

EstVolvo- he's talking about the petcock opening where you drain the radiator from. I know the upper hose connector (plastic) is where most crack...I've had several crack there. To answer your question, I'd certainly try the teflon...make sure it's wound well so no piece is loose from the thread...I might try to keep the teflon near the ends of the thread, closest to the opening where the allen key socket opening is. I think it's worth a try. Let us know how it goes!

Post by **tryingbe** » 20 Jan 2017, 23:46

Replace the o ring AND add teflon tape.

Post by **abscate** » 21 Jan 2017, 02:10

Those petcocks are pretty weak. When I grunged the threads on my 99, I just JB welded the whole thing in and used the lower rad hose to drain. I had to drain the coolant and rinse with water, dry first.

A string of teflon tape in the cooling system is no big deal, the water pump will chew it up. Worst case is it might get stuck in the thermostat but if that happens you must be stealing eyelashes from children or something else evil like double parking in Queens.

Post by **theWIFES_S70** » 21 Jan 2017, 17:42

abscate wrote:Those petcocks are pretty weak. When I grunged the threads on my 99, I just JB welded the whole thing in and used the lower rad hose to drain. I had to drain the coolant and rinse with water, dry first.

A string of teflon tape in the cooling system is no big deal, the water pump will chew it up. Worst case is it might get stuck in the thermostat but if that happens you must be stealing eyelashes from children or something else evil like double parking in Queens.

Oh Steve... I don't double (or triple!) park during alternate side street parking days anymore. I've gotten in the habit of parking a mile away from my home on those days! (If anyone is interested in finding out about parking culture in NYC, just click here... http://www1.nyc.gov/nyc-resources/servi ... t-cleaning

I'll JB-weld the mother tomorrow! Thanks for the direction. I was going to go with teflon tape, but I think locking/gluing the petcock in place is probably safer! I'll post some before and after pictures!

RigsPGT · Post by **RigsPGT** » 21 Jan 2017, 22:06

I've used teflon on mine and it still drips here and there. I might try a bolt with a softer washer or smth as it is driving me nuts. Give it a shot tho, it might work for you! Make sure to wrap a good amount of teflon around it.

Post by **theWIFES_S70** » 22 Jan 2017, 08:01

RigsPGT wrote:I've used teflon on mine and it still drips here and there. I might try a bolt with a softer washer or smth as it is driving me nuts. Give it a shot tho, it might work for you! Make sure to wrap a good amount of teflon around it.

Rigs, thanks for writing. Good to know that teflon is an option. Are you aware of a reason why it might weep more than usual? Like is my car running hotter (or colder) than it should be? Is the system more pressurized than it should be? Or is simply weeping, contemplating its eventual demise...

Post by **98v70dad** » 22 Jan 2017, 13:27

JB weld was my first thought - I've fixed many things on a car with it and was successful with it in most cases. Once you use it though you're committed. High temperature RTV sealant that is compatible with coolant (if there is such a thing and I think here is )may be another way to go that could be undone if necessary.

RigsPGT · Post by **RigsPGT** » 22 Jan 2017, 22:53

Marco,
I haven't looked closely as to why mine is leaking and at first I thought of replacing it with a new one although I didn't see anything wrong with the current one. I too, get variations in the actual leak. At times it doesn't drip at all, other times will make a 1-2" size puddle.

98v70dad,
My issue with JB Weld is that you have two different materials and when one heats up it expands and if both materials are not chemically the same, the rate of expansion and contraction is not the same thus making JB Weld let go. Now RTV (grey for water pumps and thermostats) might be a better candidate and i will try that before I go the bolt way. I'm still running on distilled water (had to put some silicone hoses) so for me it won't be an issue.