Coolant Leak around Thermotime Switch

[jwrayth]

Trying to finish my VoD job and having a miserable time fighting some coolant leaks. Most of them were just needing some tightening up, but I have a persistent leak at the thermotime switch where all attempts to fix it have failed. The short version is;

• Pressure testing at 15 psi
• New Water Pump
• New Thermotime Switch/Water Pump Adaptor
• New Thermotime Switch
• New copper washers for adaptor and thermotime switch
• Definately leaking from here. Watched droplets form with an inspection mirror whilst pressurized
• Doesn't leak whilst not pressurized

No matter what I try I can't get the thing to hold pressure when using my coolant pressure tester. 15 psi and it starts to dribble. I've drained and re-tested more than once with PTFE, liquid PTFE, coolant sealing loctite, slight variant sizes on the copper washers. I wasn't sure if I was over-tightening or under-tightening, but I definately overdid it once as I stripped the threads on my OEM thermotime switch and needed to purchase a new one.

I'm tempted to go back and try a fibre washer like my old pump had, but in my exhaustion I thought I'd take a break and check on here and see if there was any wisdom I am missing. I'm sure since I've not really seen any threads on it that it's another unique problem to my car (that seems to be a pattern these days)

[David T]

You must use the correct hardware. You can't use teflon tape, silicone, pipe sealant or anything else that may interfere with the T/T switch being electrically grounded. Refer to section 2-2-1 in the Parts Manual for the correct hardware. You should not have to over-tighten anything to get a good seal. Figure out exactly where the leak occurs.

[jwrayth]

I appreciate you're trying to help, but I started out with DMC.Eu vendor hardware by the book. Still leaked.

Leak occurs between the adapter copper washer and the water pump face. New pump, new washers, new adapter, new thermo time switch.

Only tried ptfe today out of desperation having gone through 6 copper washers already trying to get this damn leak stopped.

[chris williams]

Where these fitted with any threadlock compound of any sort as new?
Chris

[jwrayth]

No, on the first two attempts I put them in with just the copper washers for sealing (new washers each time, to be clear). I tried some loctite on the third and fourth attempts after advice from Ed. Leak was less bad but still forming drips within minutes of being raised to 15psi.

At this stage I'd be happy to follow idiot proof instructions if there are any because it'll be the seventh time trying this and it just won't seal.

[AugustneverEnds]

Did you have any difficulty removing the old thermotime switch? Maybe the threads in the hole are damaged enough to be preventing a tight seal

[jwrayth]

Did you have any difficulty removing the old thermotime switch? Maybe the threads in the hole are damaged enough to be preventing a tight seal

No I didn't, but as I said it's a new switch, adaptor and pump with the old ones sitting on a shelf in my parts cabinet. Threads in the new pump haven't looked warped as I've inspected each time I took things apart (I have been constantly worried about over torquing, after an incident elsewhere in my VoD journey).

I think I'm going to have to pull the pump anyway as coolant spilled down underneath it on my most recent drain and I can't easily reach in to clean it. Perhaps I should cut my loses and return it for a replacement unit or refund. I mean, I'm not seeing any history of problems here online for DeLoreans or any other PRV equipped vehicle and after 6 attempts I'm running out of ideas since screwing something in with a copper washer has never caused me this much bloody trouble before.

[Drive Stainless]

And we're sure it's the thermotime switch and not the thermostat housing or adjacent hose clamp, right?

[jwrayth]

And we're sure it's the thermotime switch and not the thermostat housing or adjacent hose clamp, right?

100% sure. As soon as I pressurised the system the bottom edge of the copper washer starts to gleam in a wet green colour.

No visible signs of leakage from the thermostat housing or from the hose above.

[jwrayth]

Decided to pull the pump this morning, and a good idea it was too. Source of the leak identified; On the upper edge of the TTS port there is a chip in the aluminium casting that makes part of the recessed section before the threads. I hadn't noticed it due to the angle needed to see it (which was easy with the pump out the car, but not so much with a mirror when it's installed).

Time to send the pump back for a refund and purchase from somewhere else and start all over again.