I would assume overheating. But my ECT fluctuates a lot whether driving or idling. I thought mb it was just from low coolant. Add more and no change.
Is it possible the water pump is not working consistently or maybe the thermostat?
I normally see about 192 but lately it drops to 183, 187 and no heat out of defrost. Blows cold air. Then randomly it will change to warm air. I'm not sure, but it seems when I am accelerating it heats up.
Could headgaskets cause these symptoms? I have an EGR delete. Just replaced oil cooler this spring. Had headgaskets done 2nd time when oil cooler was done in spring.
I think you can see flow into the degas bottle via the upper return line.
I've been trying to figure out if my coolant filter needs changing,
so I've been experimenting myself. Hopefully others will chime in.
It's "warm" again in FL, so I can pop the hood tonight and check.
"less" than 1 gallon, but it will also empty your degas bottle, so depends on how
full that is.
How old is your coolant? Might be a good time to do a flush and re-fill.
I replaced my t-stat during a coolant flush cycle, so I didn't have this issue.
I would drain from the radiator drain plug/spickot rather than make a mess.
Plan on 3 to 3.5 gallons JUST IN CASE. The degas bottle can hold almost a gallon depending on it's level.
FWIW--If the temperature is really cold where you are (Canada, right) that might be part of your issue. You might even try something simple like a piece of cardboard in front of the radiator as suggested by a well known FTE resident.
just redid the oil cooler, headgaskets and egr delete in early summer/spring. So coolant is ok. After the oil cooler was replaced I still noticed a delta usually of 15º when cruising at 70. Never more. So truck seems to keep it within the wanted range. I just saw most guys had mb 6-8 when cruising. I thought mb the t-stat was part of the culprit for this too.
I never had problems in even -20ºF before. I would expect some drop when driving into the wind etc. but not when going slower. I thought mb it was a cheap fix to see what happens. Not excited about dumping fluid in this cold weather though. lol I work in the driveway on the truck, no garage.
I noticed a very small amount of coolant around degas cap. If my headgaskets have gone again I am gonna scream!!!!! I cleaned it off, took the truck for a hard romp, got boost to 28 (Powermax). Got home checked again. Low and behold same amount. No more than the ring a cold beer would leave on a summer day.
If I have an egr delete does this mean gaskets argh? I was told by ford my heads were well within specs. 0.002" and they tested for cracks etc. I used the black onyx gaskets.
I'm thinking it's the thermostat or maybe the water pump. It's an early year '04. How is the reliability of those pumps? I'll check the flow of the intake in the degas bottle tomorrow and see if it's consistent.
THere is also a big of belt squeaking when the truck is idling until it reaches normal temps. I just had the belt replaced this summer because of some previous squealing. Would a bad water pump cause that sound on the bel at startup?
I'll also check the degas bottle. I had the cap tested and it held 16 psi but maybe the bottle itself is leaking abit.
Spraying the lube wouldn't hurt IF you can keep it off of the belt. If the bearings are seized, then it probably won't help.
Changing the thermostat is fairly cheap and if it isn't the problem, you have a spare for the tool box.
Here is something I was told (haven't verified it, but it sounds logical):
A good way to check for a weak water pump:
1. Monitor your EOT and ECT.
2. On a cold start both of them will be pretty close together.
3. Go out for a drive, both the EOT and ECT should stay pretty close together, usually the EOT will lag behind 10-15 degrees if everything is normal.
4. As the engine gets closer to operating temp the EOT will catch and pass the ECT, but should stay within 15 degrees of the ECT.
5. If you are running down the road after a cold start and your ECT takes off rapidly up to 200 degrees, say within a mile or 2, and your EOT is lagging way behind, say like 120 degrees, you have a lack of coolant flow, probably a bad water pump (but it could also be a stuck thermostat, plugged up radiator (internal), your radiator fins (external) are clogged with dirt, or seized idler or tensioner pulleys).
6. Also, disconnect the small hose from the intake manifold to the coolant degas bottle at the bottle end. Start the engine and check for coolant flow out of the hose. You should see a pretty steady stream of coolant exiting the hose to indicate the water pump is flowing coolant. If you see no flow, the pump impeller is most likely cracked.
So I checked the coolant flow as best as possible. It was hard to see with all the steam in this cold weather. But the coolant does seem to be pumping into the bottle. It's not a steady stream like a garden hose or faucet. It has a steady stream, stops for 1/2 sec then repeats the flow for a couple seconds.
The belt or pulley squeaking stopped when it got up to normal temps.
EOT only lagged behind about 10-12º and once they both got to about 187-192 EOT stay the same or 4-6º higher.
So would this mean the thermostat is probably not working properly? I think it's the original one. I have never changed it that I know of. Truck has 140,000 miles on it.