'04 V8 Overheating...already searched

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chilly460

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Hello All -

New guy here. I have an '08 V8 that recently has had some overheating issues. Actually, it has the degas bottle issue this winter, I put a new one on a few months ago.

This Thursday it was running normally and started bubbling out the degas bottle and temp gauge spiked. Had it towed home and ran it, overheated but I didn't see any leakage from hoses or water pump. Figured it had to be the thermostat, so just finished changing that with no improvement...immediately overheats. Fan is working fine.

Soo...any way to diagnose the issue further? There's no water coming out of the pump, but that's my next thought as far as the cause. I didn't really have time to look at it, how hard is the pump to change? Looked pretty simple with a few bolts around the perimeter but it's tough to see it fully.
 
It's a cheap fix--$7 and some change at your local Lincoln dealer for a new coolant reservoir cap. Or you can tighten the cap periodically. The seal on the cap is starting to go, which allows pressure to escape from the system, which allows the coolant to start boiling. I just went through that on my '06.
 
chilly460 said:
Hello All -

New guy here. I have an '08 V8 that recently has had some overheating issues. Actually, it has the degas bottle issue this winter, I put a new one on a few months ago.

This Thursday it was running normally and started bubbling out the degas bottle and temp gauge spiked. Had it towed home and ran it, overheated but I didn't see any leakage from hoses or water pump. Figured it had to be the thermostat, so just finished changing that with no improvement...immediately overheats. Fan is working fine.

Soo...any way to diagnose the issue further? There's no water coming out of the pump, but that's my next thought as far as the cause. I didn't really have time to look at it, how hard is the pump to change? Looked pretty simple with a few bolts around the perimeter but it's tough to see it fully.
Click to expand...

Are you bleeding the system correctly? If not, your immediate overheat could be due to a bubble in the head(s).

I just changed a radiator and water pump on a V6, the pump comes out pretty easily, once you remove the hoses and in my case, the fan/shroud assembly, which was out to change the radiator. The water pump only has hoses attached, there are no ports to the block from the pump, which is kind of cool. There were two different pump prices in the aftermarket. Around $50-60 and over $100 more than that. I bought the cheaper one, and ended up transferring the front half of my old pump to the new one, which came through without the snout end of the pump attached. That was the difference in prices. The most expensive one also appeared to come with the outlet hose attached, in addition to all the metal parts.

I'm not sure how much different the pumps are, and I will add that the old pump, with 151K miles on it, was like new! No shaft play in the bearing, no seepage, and a squeaky action when turned, like it had a brand new seal inside of it on the shaft. I only changed it as a PM task, since I was in there. I also swapped out my original belt, which was not too bad, either.

Hope this helps. But I would double check for air bubbles being bled out 100%. Apologies if you already knew how to do the bleed properly.
 
I didn't bleed it. When I changed the degas bottle, I just ran it and refilled as necessary and it was ok so I didn't think anything of it. I just found the bleed procedure and will give that a shot, thank you for the heads up!!
 
Figured I'd follow-up here. I did bleed the system as described in the service manual, and that seemed to help. I basically stopped driving the car because between multiple coil issues, and the overheating, I lost any confidence in it. Fast forward, I bled the system again recently, seemed to be OK for awhile, but it has "randomly" gotten hot on two occasions. This last time, I couldn't bleed out the air bubble and it has gone to the dealer. I hate taking my car to the shop, but no choice on this.

So today they've pressurized the system and bled it, only to have it get air in the system and run hot. I assume since they've pressurized it and not found issues, it's not an issue with the plastic thermostat neck, etc? Any other ideas out there, from the vast database of fixes to these cooling systems?
 
Well, if they are really sure that it holds pressure (15 PSI) and there are no leaks, then the next guess would be that exhaust gas is leaking in via a head-gasket breach.

Head-gasket problems with the 3.9 are virtually unheard of. but if you ever let it run too hot for too long, then it's possible.
 
OK, car has been with the dealer for a few days.

1) It's holding 15psi, no air leaks
2) Air bubble is purged
3) Head gasket is OK

It still over heats. Anybody have ideas? They want to change the thermostat housing and radiator. Issue there is around $2k in cost, and there are ZERO guarantees. I can't believe there'd be a flow issue with the thermostat housing...and I've never heard of a 7yr old modern radiator having issues. And both would introduce an air bubble in the system again, so I'd have that issue to deal with again. I normally do work myself, but working to open a business right now so I don't have time.
 
$2K??

No way in hell does it cost that much.

Go somewhere else and change the thermostat, thermostat housing and the other parts. The cooling parts are plastic and fail all the time. My 06 already had the t-stat replaced.
 
You should be able to replace all of the cooling system parts (including radiator, water pump, plastic parts, thermostat, ...) yourself for less than $1K.
 
did they even test the radiator? it shouldn't really be a mystery if it will fix the problem or not.
 
1LoudLS said:
did they even test the radiator? it shouldn't really be a mystery if it will fix the problem or not.
Click to expand...

Yeah, I don't really understand that part either. All of this stuff is testable.

I guess the assumption is that the leak is only under circumstances that they aren't able to duplicate in the shop.
 
It has a new thermostat in it. If it's holding pressure, how is changing the thermostat housing going to help?

They did a pressure test, what other test could be done on the radiator?
 
chilly460 said:
They did a pressure test, what other test could be done on the radiator?
Click to expand...

they should be able to test to make sure that the coolant is actually flowing through the rad, if it was clogged, it should be pretty easy to find out.
 
I had this issue before check these before buying anything else. Remove the upper radiator hose and inspect. Make sure the middle part is nit clogged or just run water through it. Remove the thermostat housing and replace all rubber washers see if you see any cracks in it and most likely when you remove the housing there is another plastic neck that goes to the engine and that maybe cracked remove and inspect and replace the parts. I had to replace all plastic parts and hoses including the lower radiator hose with engine cooler and that finally fixed my issue. I got the parts from rockauto it was 350 for everything except the radiator didn't. Need to replace that and its a very easy to remove and replace. Usually word of advise is that when the degas bottle goes you should replace all plastic parts. And then your good for another 80k.
 
1LoudLS said:
they should be able to test to make sure that the coolant is actually flowing through the rad, if it was clogged, it should be pretty easy to find out.
Click to expand...

At the very least, you do the simple test of measuring the temperatures of the two radiator hoses. One should be hot and the other relatively cool.
 
chilly460 said:
It has a new thermostat in it. If it's holding pressure, how is changing the thermostat housing going to help?
Click to expand...
The root cause of my occasional overheating problem turned out to be a leak in the thermostat housing, but I had a noticeable amount of coolant disappearing (I have to say that I really dislike the placement of the degas bottle--the shroud made it a PITA to check to coolant level when the location should have made it easy to check). It was repaired under my PowertrainCare ESP, so I have no idea what it would cost.

I would think that would show up under a pressure test, though.
 
I had a similar problem and the thermostat housing was the cause. The one of the two ears on the inside of the housing that holds the thermostat in place was broken. So the coolant was not flowing properly. It took me 15 minutes to replace it, 20 minutes to bleed it out and no problems since then.
 
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