Well today is the first cold day I drove my truck since I bought it. I noticed it takes a while to warm up. It'll get a little above the C line within 5 minutes of running, but then won't go much higher than that, even when driving. The heat is luke warm, and I noticed, when I parked it at the gas station and kept it running, the heat got a bit hotter. I'm pretty sure the thermostat is stuck open. Would anything else cause this? It's getting a bit chilly here in MI, need to get this fixed.

If it is the thermostat, is it pretty easy? I've only done thermostat work on chevy's. The motor is a 4.9 I6.

Thanks

 

A stuck thermostat could be the cause. You might also be looking at plugged or at least partially clogged lines going to the heater core.

See if a new thermostat does any good- if not, then I'd recommend flushing the cooling system. Sorry but I can't help you out on how difficult it is to change as I don't have any experience with your particular size motor.

 

the thermostat on a I6 is right on the top of the engine
ive never had to replace mine but it looks alot easier than a v8

 

It's not hard. Can someone please take a picture of it for him? I would do it but my internet is puke (hughes net sucks).

 

I just bought a new thermostat and gasket and I'll do it tomorrow night probably. I just got done doing the ball joints, u joints, front bearings and seals, so I'm pretty sure I can handle a thermostat replacement. I just wanted to make sure there wasn't any tricks or surprises.

I'm pretty sure it's the thermostat, because I am getting heat from the heater core, just not as hot as I think it should be. The temp gauge is what I'm concerned about. Even after running errands for an hour today, it still didn't come up to operating temp. (I'm assuming it should be somewhere in the middle?) So either the thermostat is stuck open or the guage is bad, one of the two...

 

A stuck-open thermostat is a lot better than a stuck-closed thermostat

My heater hasn't heated up in a timely fashion either. I just replaced my heater core.

Might have to do the thermostat like you.

I don't have the manual on me but I believe the 'stat is on the block under the valve cover ('89). Here's a PIC.


Ford Truck Enthusiasts Forums - Ricache's Album: Garage - WIP89I6 - Picture

/Ricache

 

First picture shows the two bolts that hold the thermostat housing on the front of the head.

Second pic. shows the housing removed.

Third pic. shows the thermostat. Note it sits in a small recess in the housing. The thermostat in the picture is broken. That is why the spring is popped out.

 

Better more detailed pics than than mine and much more graphic! That's a grody 'stat. Probably had other components of the cooling system that looked similar.

/Ricache

 

I have an I6 and mine doesn't get above the c on the temperature gauge in 110 degree weather (louisiana). I put an aftermarket gauge and it runs between 140 and 160 in summer and in winter I'm lucky to see 140. I took off my motor fan and put electric so in the winter I can leave them off till it warms up. helps a ton just you can't forget to turn them on.

 

Hmm. Anybody else with an I6 have this problem as well?

Thanks for all the pictures!

 

do not break off a bolt.

it will ruin your day.

soak with penetrating spray of your choice.

optionally heat them up.

 

You have to get that fixed or you will have serious problem in the future. Running a gas motor in that temp range will cause excess wear on the cylinder walls, the combustion chambers aren't hot enough so the motor will produce a lot more carbon, clogging up the cat, exhaust, and EGR system, and your fuel mileage is in the crapper because the engine is always running in open loop.

Your engine needs a working 195 degree thermostat.

 

Is PB the penetrating spray of choice 'round here?

Don't even want to think about breaking a bolt at the 'stat.

/Ricache

 

195 thermostat is what you need as andy said.

just look at how nasty the pics are of that thermostat and housing.

the bolts don't do any better.

 

I put the new thermostat in tonight. I haven't fully tested it yet, I ran out of daylight and my g/f had supper ready. But I will see tomorrow on the way to work. For reference, where does the needle on the temp gauge usually sit on your truck?