Weired overheating issue Ford Focus 2.0

MYBAD79

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Ok, I bought this Focus with a overheating problem, got it dirt cheap so I figure it's worth fixing even if the head is cracked (that's what the previous owner was told)...
I'm not convinced there's anything wrong with the head but here's what the engine does:
First off, oil is clean, no signs of water, does not blow white smoke.
Engine runs fine, warms up normally and runs at normal temp for about 10 minutes, temp gauge at middle.
Took the cap of the overflow tank to look for bubbles which would indicate a blown head gasket - no bubbles ....
Then the temp starts rising and both fans come on but the temp keeps climbing until I shut it off before it goes in the red...
Now the water in the overflow tank is boiling...

At this point I'm thinking it's the radiator, maybe coated with crap on the inside or the cooling fins blocked ....

Other ideas?
 
Stuck/sticking (closed) thermostat?

Can you see inside the radiator with the cap off?
 
Stuck/sticking (closed) thermostat?

Can you see inside the radiator with the cap off?

The water in the radiator gets hot too so I did not think the thermostat is bad. And no, the radiator is tucked in under the sheetmetal and it has a plastic expansion tank.

My plan of attck is to pull the old radiator and pour some acid in there to see what comes out .... I already have a new radiator ($45 with free shipping on Amazon, wonder how they make money on this).

If the old radiator is clean then I'm clueless, cannot think of anything that fits the symptoms...
 
Water pump?
Got a thermal gun to check temps of the block and radiator to compare when the overheating starts where?

I have to see if one of buddies has a thermal gun, otherwise a good excuse to buy a new tool :)

If it was the water pump I would expect it to heat up quicker and the radiator to stay cold - i read online that these have plastic impellers that often erode so you get less flow... It is a possibility I guess but again I think the radiator would then be relatively cool ...
 
Before you tear it apart, make sure there is no air trapped in the engine. I had a Renault for a year or two in college and it would get an air pocket when refilled.
 
[ame]https://m.youtube.com/watch?v=fIvhgYHftWQ[/ame]

Apparently it's common.
 
Update:
It's not the thermostat, the water in the radiator gets hot too so there is flow.

I replaced radiator and waterpump, together under $100 and not that much work .... Old water pump was fine although I read that the plastic impellers often erode .... Old radiator was flushed with acid, nothing came out, obviously there was no crud in there either ....

Still overheating .... Water flows, fans come on .... Ok time to pull the head

Pulled head yesterday, even though there are no signs of a blown head gasket or cracked head.... I read it is possible (but not common) that a small leak would allow combustion gas to be forced into the coolant, but the leak could be small enough so that water does not make it into the combustion chamber (lower pressure in coolant system, very high pressure at combustion) ....

So after pulling the head there no obvious signs of a leak, haven't sern any cracks, gasket looked ok ....
 
Some sort of a blockage in the block water passages? I think the IR thermometer is a good idea - figure out where the overheating is starting, and you might be able to pin down the cause.
 
Some sort of a blockage in the block water passages? I think the IR thermometer is a good idea - figure out where the overheating is starting, and you might be able to pin down the cause.

Yeah I guess I should have tried that before I took the head off .... Lol


I think now that the head is off all I can do is verify it's not cracked, has a flat sealing surface, not warped and reassemble with new gasket and new headbolts .... See what happens
 
Grab one of those cheap bore scopes and look around inside any passages while it is open. I've only just used the one I bought a few times, but it paid off.
 
Is it single cam or twin cam engine???? IF single cam, make damn sure the machine shop fixes the valve seats.......I have had TWO of those engines that upon reaching 150k miles eat the valve seat, and in my wife's case I had to replace the entire engine.....in a friend's case we got lucky and replaced #4 piston/rod assy.....and of course got the head reworked......

Wife now has a twin cam 2.0 in her 01 Focus.......so I am curious as to what you find.....
 
It's a DOHC 2.0 and I found the head on Ebay, $325 shipped rebuilt, resurfaced etc ... Incl lifters and cams .... tempting ....
 
Update: head looked good, cleaned everything, blue checked head to block surfaces, good contact, not a warped head .... Ni obvious sign of a leak anywhere ....
Ok, pretty much gave up and reassembled with new gasket and new bolts , started it up, ran fine for ten minutes and again overheated .....

No more bubbles in the cooling system though .... Hmmmmm

Ok, now I was wondering if maybe maybe maybe the thermostat was stuck .... In theory the previous overheating could have f'd it up ????? Anyways, took it out, drilled two good size holes in it , reinstalled .... Voila .... Fixed .... Idled fine for almost an hour, no probs .....

So I'm guessing it was both, head gasket and bad thermostat, the thermostat alone wouldn't cause the bubbles and it probably would take less than 10 minutes to overheat if it was only a stuck thermostat .....

Anywsys, it's fixed finally .....
 
Nailed it! Post #2 :bounce:

Yes you did .... I have to admit I've never seen a thermostat doing this, I did not think that with a stuck thermostat it would take over 10 minutes to overheat, maybe it did stick intermittend .... The water in the radiator got hot so I assumed there's flow ...
Maybe it was both, head gasket and thermostat... No idea just happy it's finally running ....
 
In my '72 350 engine vette, I had some issues, and found the NEW stat in the car was still allowing over heating....well in the fight, I found the stat was in fact opening at like 212 or so on the stove with a IR gun and pot of boiling water....lucky to see it then....it was rated at 180....so much for China junk....

running the car with NO stat now....

seems fine....on that score, anyway...

:cussing:
 
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