Hello,

This is probably an easy question. I took my truck in to get the coolant system flushed and now I am having some warm-up issues. Here is the new warm up cycle and symptoms:
1. When truck is cold the gauge does not move from cold for about 5 minutes.
2. Gauge jumps to a really high temperature for about 2 seconds. Yesterday the temp light went on for about 2 seconds so I pulled over to shut the truck off but it dropped almost instantly.
3. Gauge drops to normal operating temperature for about 5 seconds.
4. Gauge slowly drops to cold again.
5. Gauge slowly moves to normal operating temperature. about 8 minutes total.
6. After driving, it looks like a small amount of coolant is spraying out of the cap.

Here is what I have tried so far:
1. Coolant level was low so I topped it off with about 4 quarts of coolant and water.
2. I took it back to the shop and they opened the cap and tried to get the system to "burp". Let it run for about 10 minutes with the cap off and then added about 2 quarts of coolant.
3. Thermostat appears to be opening and closing okay

Any thoughts on what may be causing this issue?

Thanks ahead of time.

 

Air bubbles in the system. Once they work out, the system will return to normal.

Steve

 

That's probably all it is, and not to scare you, but I had the same thing happen... right after a flush (could be coincidence) and it turned out to be exhaust gas leaking into coolant... blown head gasket. Confirmed by a chemical test of the coolant (cost about $50 for the test).

 

Thanks for the replies, I hope it's not blown head gasket, but I'll keep that in mind. Do you think maybe the coolant cap needs to be replaced? Or is that unlikely? Thanks again.

 

This happened after I flushed my radiator. The gauge would not move at all, then go really high, then down again.

Stop the engine, take the cap off, and squeeze the feed hose on top of the radiator. The air typically collects there and giving it a squeeze often "burps" the air out.

If you added a gallon of antifreeze, it sounds like the dealer or whoever flushed it was being quite stingy with the coolant. Sounds like they drained it, filled up the radiator and gave it back without any purging whatsoever.

 

Thanks,

You're right, they were stingy on the coolant. Is there any other place to add coolant right into the radiator like the old days or do you have to add it through the overflow?

 

You can add it straight to the radiator. It should be filled right up to the cap so just do your topping off there. Just be careful, even though the caps are designed not to blow off they will vent hot steam and near boiling coolant from a hot motor. If you must take it off when hot, get a heavy rag over the cap, and then twist.

 

Just to follow-up and finish this thread...

After the dealer misdiagnosed twice, they finally figured it out. The problem was the bottom half of the radiator was getting plugged up. This was likely caused by the chemicals used when the flush was performed. The flush probably loosened up some rust which settled at the bottom of the radiator. Everything seems to be functioning normally now. I had the dealer perform a test to see whether the head gasket was damaged and it is fine. Phew! Thanks for all the help...

Rob K.

 

Well, I thought the problem had been fixed but the engine started into the same overheating pattern again recently. I took it into the dealership and got the news...bad head gasket. My theory is that there is a small leak in the head gasket which closes when the block heats up enough (overheats). Unfortunately, the mechanic used a block tester and an exhaust tester and found coolant in the exhaust and exhaust in the coolant. This is real bummer because I think the transmission is going out too.

 

If the shop ran the truck at idle for 10 minutes with the cap off, it probably overheated sitting in the stall. I would be very upset if that happened to my truck. The cooling system has to be presurized to take away maximum heat and not boil. Blown headgaskets are a sure sign of overheating too.

Just a thought
-Patrick

 

Good thought...that's probably what happened when I had the coolant system flushed. Now I'm trying to decide if the truck is worth a new or rebuilt engine. I suppose it's cheaper than buying a new one...maybe.

 

you would be suprised on how much shop costs are for a engine overhaul like that. Sometimes its cheaper to just find a used stock engine and throw it in yourself.

 

What year is it? Engine and tranny will set you back. Maybe trading it in would be a good idea..

 

The stealership quoted $5400 but I'm going to call around this week and get some more reasonable quotes. I'm sure it's going to cost a ton. Other than this issue the truck is super clean. It's a 97 with 100k. The best part is its paid for.

 

If I decide to fix it I will likely put a new or rebuilt engine and transmission in it. I agree that it will cost too much just to repair it. Maybe I can take the opportunity to get a more powerful engine.