It runs fine and overheats at varied times - Hi All, First of all, I want to thank you for this site. I have been a member for several years ...

Hi All,

First of all, I want to thank you for this site. I have been a member for several years and have used the site to read up on issues I was having and it has been very helpful.

So, now I have an issue that I have not been able to find any posts that quite match up. I don't want to make this long and boring but feel a little history would be good. I have had my truck for several years and it has been great. last summer the lifters started making a lot of noise, I just didn't have time to tear it apart myself, so I took it to a garage. A few lifters were toast, the mechanic showed them to me and it wasn't good. He assured me the cam was OK and he replaced all of the lifters, put her back together and I gave him $2,600 in July 2020.

When I got it back, I noticed when I started it, it would run rough for a few seconds and then it would smooth out and run fine. Then, 2 weeks later I was pulling a trailer and the message center on the dash said that the engine was overheating and the A/C was shut off. The temp gage was pegged, I pulled off to the side of the road and it went right back to 210 degrees. i was obviously concerned so I pulled into the next gas station and it was about 1 gallon low on coolant. Filled it up and it was fine. Then it seemed every 2 weeks or so I would have the same issue. Fill it with coolant and it was fine. I took it back to the same mechanic for an oil change and told him about the coolant issue. $200 later he told me that he found a pinhole leak in the upper radiator hose so he put a new clamp on it and changed the oil That was in mid- August 2020. I have never found any puddles under the truck, so I don't know what is leaking.

Since that time, I have had to add a gallon of coolant every 2 or 3 weeks. It overheats at random times and is getting more frequent. By random, I mean sometimes it will overheat 3 times within a 10 mile drive, as soon as I pull off to the side of the road it will drop back to normal. Other times, I can drive 90-100 miles and it will not overheat at all.

So, I started to think it was the thermostat. But why was it so random?? So, I replaced the thermostat and it was good for a day, then it started again.

Will a water pump fail at such random intervals? That just doesn't make any sense to me. The water pump doesn't appear to be leaking and it doesn't wiggle when I pull on the pulley. the cooling fans seem to be working good, The oil is not milky and tonight I pulled the plugs and they all seem to be OK. Probably not the best but not fouled or clogged up.

I am really thinking on replacing the water pump, but I don't want to just throw money at this.

I have never claimed to be an ace mechanic, but I am not stupid either. Right now, I am confused.

lgeist wrote:Hi All,
it was about 1 gallon low on coolant.
I have never found any puddles under the truck
I have had to add a gallon of coolant every 2 or 3 weeks.
The oil is not milky
.

You are burning through coolant. A gallon every 2-3 weeks is a huge amount of water. You’re not seeing any water on the ground. It is going somewhere. If you don’t see steam coming from the exhaust, and it’s not in the oil, it is going somewhere. Are your passenger side carpets wet? Maybe the heater core cracked, but I would think you’d noticed a gallon of water on your carpet.
I feel your mechanic owes you $200 back for the upper hose he replaced. And He needs to diagnose the problem for free. I say free, because I believe your water loss is due to his work. Or a failed head gasket, hard to determine if that is his fault or not.
A leak down tester is needed here, and driving it, constantly overheating, and having to add that much water is not good. Maybe one of the steam lines connecting the heads is leaking, but I would think you would see water on the ground.
There is an issue. No engine goes through gallons of water. Ever.

First place I'd look is where those stupid plastic heater hose connectors are located, and not a question of IF but WHEN they will fail - and that will be very soon - if not already. Replace with metal ones found at:
https://www.rockauto.com/?mfr=DORMAN&partnum=800409HP
Very common problem, and they have a high failure rate.
I was losing coolant a while back, but could never find a leak, or puddles on the ground.
Then one day when I was checking the ATF level, the engine was hot and running - and out of the corner of my eye I swore I saw a little drip or a puff of steam or something. Broke out the flashlight and started poking around. Well, guess what is right by the ATF dipstick tube. Those ridiculously cheesy heater hose connectors. The plastic was so brittle it was like poking at a rotten log. It's as if GM intentionally found the cheapest and worst plastic possible to make those connectors out of. It's a complete joke. Have pictures of them in the archives.
Anyway, replace with proper metal connectors from Dorman and never worry again.
We have to be vigilant and hard at work to correct bean counter decisions on the manufacture of our vehicles.
Imagine a $5 plastic part causing one to lose an engine.
Planned obsolescence IMHO.

CarMech97

with your symptoms, I would be concerned it may be a head gasket.

Any smoke or smell out the exhaust? Burning coolant has s definitive smell, sort of sweet-smelling. As others said, if you don't have puddles, you are burning it somewhere...

GOAT721 wrote:with your symptoms, I would be concerned it may be a head gasket.

This

It could also be the intake gasket leaking coolant into the cylinders. Did any of the spark plugs look different than the rest? You could check compression to determine if the head gasket is bad. Also you could check misfire counts on each cylinder if you have a scan tool. If you don't have a scan tool or compression gauge, I would fill up the coolant and look over everything externally than you can. Definitely check the cheap heater hose connections suggested above or anything that would drip onto hot exhaust and evaporate.

Issues that I have commonly seen are radiator side tank seals leaking ( not always as apparent as you might think), recovery tank cracked, leaking head gaskets. The heater hose connection don't seem to leak so much as just completely fail and dump coolant.

Need to pressure test the system and see where the coolant is going.

Thank you everyone!!

Like I said, I never had a problem with this truck until I had the lifter issue. My first thought was head gasket, but I wasn't smelling a real bad odor at the exhaust and it didn't steam out the exhaust either. And, that doesn't explain the randomness. I am going to try to post pics of the plugs. They are in my gallery if it doesn't work.

I do occasionally smell coolant in the cab. It isn't much but I get a whiff sometimes. So, I will go to work checking everything again.

I don't believe he put new plugs in when he put it back together but I know the plug wires were not replaced. That won't help with coolant but it doesn't run well either. Going to replace all of them today,

Thanks again, I will let you know what I find.

Larry

With plugs that clean I'd really suspect a head gasket, with the engine cold, start it up and give the top radiator hose a squeeze, if it firms up on a cold start then you are leaking combustion pressure into the cooling system. On my truck pegged is 260*F, LS's start having problems at about 230*F so if it was pegged that's definitely not good.