1996 850R - Coolant leak frustration

txdave13 · Post by **txdave13** » 22 May 2014, 12:50

Thanks. I actually picked up a new ECT and have it in my garage. I'll give it a shot.

Would the sensor lead to my blowing coolant out? Regardless, I'll change it out.

Post by **E Showell** » 22 May 2014, 12:58

Yes. Before you remove the ECT, however, disconnect the wiring connector to the ECT and check for oxidation. It may be that the connection is crudded up and simply needs a good cleaning with something like Deoxit to restore proper functioning. Please do this check before cutting any wires. . .

Post by **erikv11** » 23 May 2014, 01:09

I doubt this is an ECT problem. The ECT tells the gauge where to sit, turns the fan on and off (hence can relate to overheating), and tells the ECU how much fuel to add, but it doesn't lead to progressively higher cooling system pressures that correlate so well with engine RPMs.

Replace that ECT anyway for sure, hopefully that is the problem by some freaky circumstance, but next step should be to pick up a combustion gas analyzer kit, rule in/out the head gasket possibility. You can test it yourself in a few minutes. The behavior you describe is dead on for a one-way breach that is sending combustion gases into the coolant compartment. The only other thing I can think of that might fit would be a blockage somewhere but you've replaced too much (radiator would be the most likely culprit).

Post by **E Showell** » 23 May 2014, 08:26

I only suggest ECT problems because I had a recent overheat/total reservoir evacuation. Replacement of the thermostat and ECT fixed the problem immediately.

Post by **cn90** » 23 May 2014, 08:55

DIY for ECT is below. It can be tricky!

https://www.matthewsvolvosite.com/forums ... hp?t=52203

Post by **erikv11** » 23 May 2014, 09:29

E Showell wrote:I only suggest ECT problems because I had a recent overheat/total reservoir evacuation. Replacement of the thermostat and ECT fixed the problem immediately.

Sure, I don't mean to suggest the ECT is a bad idea, I would change it in this case too. It's so easy to do and an important routine service item anyway. I just think the symptoms are a little ominous.

Post by **tryingbe** » 23 May 2014, 11:54

Is the radiator fan turning on?

I had forgot to connect the 12v wire from the starter to the fan, a fan relay goes bad, and a fan motor seized, all cause the fan not to come on and car would over heat.

Make sure the fan turns on before buying anything else.