thermostat operation - Diesel Forum

alex3 · 12-04-2012, 07:37 AM

Hi guys,while i was out of town I had my truck in to have it flushed and the coolant replaced with ECL and I had a new thermostat to be installed. while on the road they called to say it was done and gave me the price. they were charging me for the coolant. I said to look at their work order. I was providing the coolant and they thermostat was to be replaced and I was providing that also. I got "OH". and that it would be ready a day later. Now I am having doubts as to whether they actually changed my thermostat, let alone the ELC. So can someone tell me what my water temps should look like. I have a scan guage. I think I should hit 190 degrees and pretty much stay at 190. if that is not true let me know.
thanks, alex

skanj0 · 12-04-2012, 12:29 PM

Quote:

Originally Posted by alex3

Hi guys,while i was out of town I had my truck in to have it flushed and the coolant replaced with ECL and I had a new thermostat to be installed. while on the road they called to say it was done and gave me the price. they were charging me for the coolant. I said to look at their work order. I was providing the coolant and they thermostat was to be replaced and I was providing that also. I got "OH". and that it would be ready a day later. Now I am having doubts as to whether they actually changed my thermostat, let alone the ELC. So can someone tell me what my water temps should look like. I have a scan guage. I think I should hit 190 degrees and pretty much stay at 190. if that is not true let me know.
thanks, alex

OEM thermostat begins to open at 195f, and fully opens by 218f. If up to operating temp (EOT over 190f), you should not see ECTs below 188f to 190f. If the ECT is below 188f or so, your thermostat is weak and is likely allowing coolant to circulate, as they fail in the open position.

06 GatorRving · 12-04-2012, 03:09 PM

Quote:

Originally Posted by skanj0

OEM thermostat begins to open at 195f, and fully opens by 218f. If up to operating temp (EOT over 190f), you should not see ECTs below 188f to 190f. If the ECT is below 188f or so, your thermostat is weak and is likely allowing coolant to circulate, as they fail in the open position.

Hmm so I take it mine may need to be replaced since the ECT was 182 and the EOT was 193 and pretty much stayed there for a 40 min ride at 65-70 MPH

2 Stroker · 12-04-2012, 09:22 PM

Yes yours may need to be replaced. These motors run better on the warm side than the cool side. Mine at 60mph ECT 192-194* EOT 196-198* flat groung pulling my 5er add 10* to each.
2 stroker

alex3 · 12-05-2012, 06:27 AM

Well I looked last night and there is a new thermostat in. However it is doing the same as the old one. The temps will slowly climb and get near 184 by the time I get to work ~1/2 hour and 17 miles. the same with the EOT. Outside air temp about 32. So now I wondering if I am looking at either the wrong points or if I have a different problem.

Mackskibum · 12-05-2012, 08:42 AM

Is your fan running all the time?

skanj0 · 12-05-2012, 09:44 AM

Quote:

Originally Posted by Mackskibum

Is your fan running all the time?

Good question, though not sure why it would. I believe the fan clutches fail in the "no fan" mode versus "full fan" mode. If it is stuck engaged that could help explain an overly-cool ECT.

My bet is the mechanic pulled the old thermostat to flush the system and then put it back on without replacing it. My truck used to run cool (low 180s) until I changed the thermostat.

alex3 · 12-07-2012, 08:52 AM

No. I can't say if I've ever heard the fan running. And unless they shined yp the old thermo before putting it in, the new one is in. Maybe I'll verify the new one I have on the stove to see if it opens at 190 and the replace the one that is in there.