I need some help or ideas as to what to look at next. I have looked at the past posts for overheating and looked at some of the solutions to no fix as of yet.
I have a 1991 Chevy K1500 Silverado 5.7. I do not have any evidence of coolant leaks anywhere. I have thus far replaced the radiator - flow is good, replaced the thermostat 195 I believe, also the rad cap, replaced temp sensor, replaced the heater core, replaced water pump and the fan appears to be working fine. I can drive this around the city for about 20-30 minutes in medium traffic with some stopping and the truck will over heat and blow water out of the cap. I have flushed the whole engine 4 times now and have opened the system up at different points to check for flow or debris. I cannot find any leaks and the oil is looking good, wouldn't a blown head gasket cause water in the oil or external leaking, also the overflow does appear to flow fluid both in and out when needed. I have recently removed the radiator and checked flow again, removed the pump to check for failure or debris and then also flushed the system in every hole I could find since I had though perhaps something is blocking the flow, it all seems to flow fine. What to do next, what new tool or tester to buy next. Thank in advance Chevy Gods, I love this truck and want it to run it's best.

 

Well you can find out if its a bad head gasket with a leak down test. I assume that the radiator hoses are new or in good shape.At that age its is entirely possible its a head gasket or warpage.No, you can get exhaust gas without oil in the coolant.It all depends on where its leaking at.Might not be a bad idea for rebuilt heads as your valves and seals are likely pretty worn out by now.

 

You should be able to find a local radiator shop that can pressure test and run some die in the radiator for cheap. I had this problem with an old fox body mustang and I sent my wife to a radiator shop (yes they still exist). They ended up confirming that I had a blown head gasket in 15 minutes and didnt charge her for the dye or test kit. Yeah shes cute hahaha

Side note, I had a problem in the K1500 and it would start to get hot in traffic, turned out that replacing the EGR got rid of the hot exhaust gases and brought the truck down to normal running temp. havent seen the gauge creep since

 

Thank Oilcanhenry, I was thinking head gaskets and intake gaskets anyway but I was always under the impression that if I had a blown head gasket I would see coolant in the oil or some sign externally that it was. I was thinking the valves and seals as well, just have to do what I can afford now. I started pulling the coolant system all back apart anyway so might as well just continue to the heads and intake. yup the hoses are all new in fact I went with an all metal flex upper since it kept going flat. Thanks for the info.

 

Hey JK1500, thank for responding, the EGR is new as well. Sadly I am in California and finding a radiator shop that will do the test proved a bit of a challenge, they all just want to replace it and since it is new they didn't want to help even when I was happy to pay for it. Thanks again for the response, I will keep looking for a good shop.

 

Ok since I already had most of the engine accessories, waterpump and radiator already removed, I had a local guy I trust take a look at what i had and he suggested to remove the intake just to look and see what condition it was in and it might just be a simple intake gasket issue we could replace easily. as soon as i removed the intake and looked at the block I saw something that might make since as to why I am overheating, what do you guys think ? I attached some pics showing the rear of the block where the intake mounts and if you look you will see a cover on each side that is sealing the coolant passage for the rear, is this normal ? I have done about three intakes in my life and have never seen anything like this before. The last pic shows a large clump of burnt something as had the same thing on the other side as well, it removes easily but wondered if this indicates something I should be concerned about too. Thank for any info or suggestions. I will probably be removing the engine and just tearing it all down and rebuilding as I get spending money.

 

Normal, if you look at the intake you will see that there is no coolant passage in the rear. The area where the crud is gets hot because of the exhaust gases passing through those ports, I wouldn't say that I would call that build up normal, but in my experience not unexpected.
I forgot to mention, since your overheating happens during low speed stop and go driving I would suspect the fan clutch is bad and allowing it to free wheel when it should be driven pulling air.

 

ill take "when some people shouldnt touch a wrench" for 500 Alex.....

the metal tabs that someone installed on the coolant passages, should have been installed on the egr passages.

the burnt thing you see if oil crud from it overheating or poor maintenance and not changing the oil

 

Fan clutch is working fine, it is actually new. and the intake does actually have coolant passages in the rear.

 

Well I found out that the stainless metal covers on the rear coolant passages is actually normal for much colder climates I am told by Chevy. I am not real sure as to why anyone would have them in this truck since I am in California and the truck has been registered here for years from the last owner. I think he must have just ordered the wrong gasket kit and left them in. That's what i thought about the burnt oil, I'm just gonna tear it down and rebuild it.