this 'stat wont get hot enough

[mexicanjoe]

OK guys here's the full meal deal: I bought a new radiator for my '89 (aka LULU-BELLE) and while I was at it I bought a motorcraft 195* thermostat.. Its all well and good until we get this cold snap....now i Can get 120* if I dont block the radiator with cardboard! Is it my timing?? Do I need to turn up the IP?? Do I need to sacrifice a ****** nanny goat( where can I buy one?), Someone school me on what I may be doing wrong

 

[79jasper]

Fan clutch staying locked?

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[franklin2]

Diesels never warm up unless you use them. If you expect it to get over 120 on a cold day sitting in the driveway, it probably never will. Run it hard down the road and it will eventually get up there. I have a piece of OSB I have cut specifically to cover the radiator the right amount, and this piece lives behind the driver's seat in the summer. I use it when it's really cold out and need some heat in the cab. It covers about 75% of the radiator.

 

[mexicanjoe]

franklin2 i get 120* after running 12 miles of highway... I guess Ill cut some cardboard and use it as a air shield....... as far as the fan clutch being locked Ive not heard the roar that accompanies the lock up.....

 

[RetiringColt]

Mexicanjoe did you check your new thermostat prior to installing it? it could have stuck open? I know it stinks hearing this after everything is back together, but you might want to boil you T-stat and watch it's operation with a thermometer.

 

[FordGuy100]

When I put my engine back in and filled with coolant, it didn't get up to temp with the new thermostat. After driving down the road a bit, at around 100-120*F on my gauge, it shot up to 220 after about 10 miles. Turns out I had a huge air pocket, and it finally burped it out. Limped home trying not to overheat, and filled the rad the rest of the way up (no visible coolant in it, I guess a big air pocket was in there).

How long has the new stat been in and how much driving has occurred since the install?

 

[mexicanjoe]

Fordguy I bought the radiator and stat about one month ago......

 

[franklin2]

I have my fan locked on purpose with brackets. While I am sure it affects it some, it will still warm up if I am using the truck. I am assuming you are using a known good gauge? Your heat from the heater reflects that colder temp? Do you have infrared heat gun you can verify it with? I think Harbor freight has them fairly cheap.

If the thermostat is open when it should not be, your upper radiator hose will be warm and you will have coolant flow in the radiator when you pull the cap off. If the upper radiator hose is cold, the thermostat is doing it's job and you are not warmed up yet.

 

[FordGuy100]

I have my fan locked on purpose with brackets. While I am sure it affects it some, it will still warm up if I am using the truck. I am assuming you are using a known good gauge? Your heat from the heater reflects that colder temp? Do you have infrared heat gun you can verify it with? I think Harbor freight has them fairly cheap.

If the thermostat is open when it should not be, your upper radiator hose will be warm and you will have coolant flow in the radiator when you pull the cap off. If the upper radiator hose is cold, the thermostat is doing it's job and you are not warmed up yet.

Agreed. I suppose if the stat is stuck open the upper rad hose will be warm, but not hot like it would with a normally functioning coolant system up to temp.

 

[Garbage_Mechan]

It takes only a tiny amount of flow to prevent coming up to temp on these engines. This is one reason it is critical to use the Motorcraft thermostat, it seals tight when closed. Since we established you have a new proper thermostat and the fan clutch is not on it leaves a few choices. Something is allowing coolant circulation. Is the little ball present in the air bypass port? If you aren’t sure pull the thermostat housing and look. I have found new thermostats with pieces of oring, gasket or silicone holding them open. Have to pull it to see. Is there a coolant filter or anything changed from factory plumbing? Sometimes coolant filters plumbed to bypass the thermostat unintentionally go this. Of course even new quality parts fail at times so don’t rule that out.

 

[mexicanjoe]

My infrared temp indicator is where I get temp readings, not my gauge in the cluster....However when the needle hits "N" in normal its a pretty good bet the temp is about 180+. I didnt think about the thermostat housing..... guess Ill take it off and check...... should it have a rattle to it or not? ?

 

[IDIBRONCO]

I'm not sure about a rattle, but if you look at the bottom of it, you can see the ball or the hole where it used to be if you completely remove the gasket. The ball missing will not make it not reach operating temperature. I've driven mine into a 25-30 MPH wind with outside temperatures right around 0*. I have no ball in the thermostat housing and never put cardboard in front of my radiator. Not only did I have plenty of heat from the heater with it not on full blast, my mechanical temp gauge stayed right below 195*. If something was not letting the thermostat close completely, I can see where it may never reach operating temperature. When I bought my current truck, I thought the heater didn't work unless it was about 45* or so outside. I thought core was plugged until I found out that neither heater hose was even warm with the engine running, the heater on high, and after driving 15 miles. When I went to replace the thermostat, there was a piece of broken 6.9 style glow plug controller holding it open.

 

[franklin2]

My infrared temp indicator is where I get temp readings, not my gauge in the cluster....However when the needle hits "N" in normal its a pretty good bet the temp is about 180+. I didnt think about the thermostat housing..... guess Ill take it off and check...... should it have a rattle to it or not? ?

I think you are correct on that. Most of the different trucks I have had, the thermostat temp seems to be around the "O" in "normal, which would be around 190F. When it's cold outside and you first get going, you can see the needle bounce off the "O" several times as the thermostat opens, and then shuts as all that cold water from the radiator gets in the engine.

 

[Garbage_Mechan]

I have to politely disagree on the ball missing not causing it to run cold. My 86 6.9 bugged me for a while until I found the ball missing. Using IR temp gun to verify temps. It came up to temp nicely after putting in a new ball and fabbing a new retainer.

 

[IDIBRONCO]

I also know a guy who claimed that his heater wouldn't put out any heat until he turned the fuel up. After that, he said that the heater worked fine. I guess strange things do happen and can only give my personal experience.