At a loss, overheat after head job (4.0 OHV), new Motorcraft T-stat too...

[Larry Hampton]

My daughter overheated her 2000 Explorer XLT 2wd back in July. Blew a intake gasket and cracked a head. Got a new head, valve job and surface on the other. Finally back together 6pm 12-31-11!! Bled the system with new 50/50, felt I had purged it good.

Drove it for 6 miles, CEL came on, ended up being the driver's O2 sensor never got plugged back in, but it never got hot. Sat till yesterday (when I finally figured out the unplugged wire) and tried to drive it into town, 4 miles the check gage light came on, temp was.pegged. pulled over, popped hood, cap puking. Hadn't been running heater, core has cold water, started and put defrost on high, temp went to 3/4, so I decided to limp back home, about 1/2 mile it went back to 1/2 and stayed there the whole way home. Got in Festiva and went on into town.

Got back, topped off coolant with more 50/50 (about 3/4 jug) and shut hood.

Got home tonight, checked fluid again, added a pint more, the overflow was full cold. Started it up, still no codes, warmed it for a couple minutes then drove about two miles with eye on temp gage, when all of a sudden the gage looks like a tach in a drag car. Pegged again. Turn around, defrost on high, back to driveway.

My thoughts are, maybe fan clutch went bad on her, or water pump.

Shaft seems okay, fan clutch 'feels' okay. Maybe my new Motorcraft T-stat is bad? I have the old one and a new gasket. No milkshake in new oil... Cooling system isn't pressurized by compression with cap off (I rented a cooling system test prior to putting the top end together).

I'm stumped.

 

[ahodges]

If you bleed the system with the front jacked up and it continues to do that I would suggest a revised part number water pump from ford for this problem. I had a very similar problem and that finally fixed the problem after replacing everything else first with no luck. Ther is a service buliten out about it

 

[ahodges]

Check this thread out. You'll probably find it helpful. I posted the part number for the water pump Im talking about at the bottom of the second page.

http://www.explorerforum.com/forums/showthread.php?t=272433&page=2

 

[Larry Hampton]

I had an epiphany, this evening after it.cooled and I opened it up, it had a vacuum. Also, when it poked past the cap, it didn't fill the overflow. I wonder if the cap is simply bad? The rental tester didn't have an adapter for the cap.

BTW, it only has 126k on it.

 

[yavapaires]

I had an epiphany, this evening after it.cooled and I opened it up, it had a vacuum. Also, when it poked past the cap, it didn't fill the overflow. I wonder if the cap is simply bad? The rental tester didn't have an adapter for the cap.

BTW, it only has 126k on it.

Are you sure the head gaskets are on correctly? I've never had one of these engines apart, but, on some engines, the head gaskets can be installed upside down and backwards, covering the steam/water holes. Just a thought.

 

[Larry Hampton]

Okay, I read thru that thread, man, I hope it isn't the pump. I'll try bleeding the system on a hill and replace the cap, check the overflow hose for blockage. I'd like to get this solved this weekend.

 

[Larry Hampton]

Are you sure the head gaskets are on correctly? I've never had one of these engines apart, but, on some engines, the head gaskets can be installed upside down and backwards, covering the steam/water holes. Just a thought.

Yup, triple checked, plus they had 'front' printed on them.

 

[ahodges]

Are you sure the head gaskets are on correctly? I've never had one of these engines apart, but, on some engines, the head gaskets can be installed upside down and backwards, covering the steam/water holes. Just a thought.

I was asked the same thing when I was having my problems and it turned out that it wasn't the case, just a wierd water pump cavitation issue.

BTW, mine only had about 120k when this isssue arose..

 

[Larry Hampton]

Man, I already spent about $1000 on this, I dont need another $200 into it...

 

[ahodges]

I hear ya.. It's better than chasing things down and never finding a solution though. They make a cheaper solution too called a heater by pass kit or something but I've never seen one installed. I guess they quit making them too so if you go that route you will have to find the specs and diagrams on it and make it yourself. I understand it is just a few T's and more heatercore hose.

 

[my98nnj]

I had an epiphany, this evening after it.cooled and I opened it up, it had a vacuum. Also, when it poked past the cap, it didn't fill the overflow. I wonder if the cap is simply bad?

It should puke into the overflow tank and draw from it, when cooled down.

I'm betting on a bad cap too.

 

[Larry Hampton]

It should puke into the overflow tank and draw from it, when cooled down.

I'm betting on a bad cap too.

Right, plus a cap isn't that expensive, and its a heckuva lot easier to install than a pump!!

I had to change the tstat housing on my Sport Trac with the SOHC and it wasnt as hard to bleed the system as this has been.

 

[Larry Hampton]

Well, I put a new cap on today and topped the coolant off. I also checked the overflow hose, it was clogged. I pulled it off and using my compressor about 1-1/2" of gunk came out where it was pushed up against the nipple to the overflow jug. I started it and let it get up to temp with it parked nose up on a pile of dirt next to rye driveway. Shut it down and let it cool, added some coolant and drove it around the neighborhood, about a half mile, then parked it on the pile again.

I'll let it cool down fully, check the coolant, then drive it tomorrow. Hopefully its fixed now, still no codes.

 

[ahodges]

That may have got it for you since the over flow hose was plugged. crossed fingers

 

[koda2000]

i just went through the same thing yesterday after changing my lower rad hose w/truck up on ramps. apparently the engine gets air in the cooling system and it can be hard to get it out. as far as i can see there's no air bleed valve anywhere, so getting the air out is a pita. after a ride around the block it finally "burped" then the temp gauge shot up to max. i immediately pulled over and checked the rad cap (it was cool). after removing the cap, quite a bit of air came out and the overflow tank (which was now full and puking) drained back into the rad. after the temp gauge came down i went back home and waited for the system to cool down a bit. the rad then took another 1/2 gal to fill and the overflow tank took about a quart. now everything is back to normal and fine.

 

[Larry Hampton]

So far so good. Drove it to church this morning, about 9 miles one way, everything okay, pulled into the house and popped the hood, when it cooled I added about 8oz of 50/50. Plan on driving back to church tonight and into work tomorrow (22 miles one way). Hopefully all the air is out.

 

[ahodges]

Good to hear