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Overheating towing with Denali 6.2L - Losing my F'n mind!!
- Thread starter rubicon1976
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I’m an ASE certified master tech, provided that the cooling fans are working, I am fairly certain that you have a failed head gasket or a cracked cylinder head. Simple removal of the spark plugsby a qualified tech and review of the plugs will normally yield a diagnosis. The first and most simple test I do for a suspected bad head gasket is remove the engine drive belt on a cold engine, remove radiator cap. Start engine, if you see ANY bubbles you have a failed gasket or a cracked head.
Check oil pressure at idle hot. If below 20 it will go into limp mode, if below 17, it will shut down. May look like an overheat problem but really a low oil pressure problem. 6.2 motors had problems with cam bearing wear causing low OP. I had this problem with my 08 6.2. Had to replace engine do to GM screw up with cam bearings.
I would think that a cracked block or blown head gasket would show one of several symptoms........water in oil, a cylinder misfire, low coolant level from combustion gases over pressurizing the cooling system, white smoke out the tail pipe, etc. But for overheating it will be due to low coolant level from the escaping/leaking coolant if block or head gasket is suspected.
Also ASE master tech since 1991.
EfrainlCazares
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I didn't have the shut off, but the engine and transmission temps jumped to 225 and 230. I bought a three core radiator. I kept the same temp thermostat and added an additional transmission cooler. Now my normal temot in town are 150 and on the road , about 165
An easy way to see if the no start when towing is related to vapor lock is to bleed gas off at the fuel rail while cycling the key several times to on several times without starting. (as someone earlier mentioned) The safe way to do it is with a fuel pressure tester so you can bleed the fuel outside of the engine compartment. This test must be done during the no start condition. If boiling hot fuel comes out, keep bleeding until you have a steady stream. If it now will restart you found your problem. Also if you are seeing that hotter than normal temp reading after it stalls bear in mind that the temp can go up 15 to 20 degrees when you shut off a hot engine. Here is a link to another post that tells more about the vapor lock issue. http://www.tahoeyukonforum.com/threads/2007-gmc-denali-stalls-after-towing.73312/#post-1013310
OP: Any word?
I am in the process of wrapping my fuel lines right now. I attached a picture of the fuel line, just want to make sure I'm doing the right one. It also looks like there is a metal crossover to the other side of the motor. Is this correct?
Also noticed that some wire loom in the area behind the alternator was brittle and crumbled when I touched it is one that looks a bit melted. I recently replaced the alternator but could it overheat to the point of vapor lock?
I am in the process of wrapping my fuel lines right now. I attached a picture of the fuel line, just want to make sure I'm doing the right one. It also looks like there is a metal crossover to the other side of the motor. Is this correct?
Also noticed that some wire loom in the area behind the alternator was brittle and crumbled when I touched it is one that looks a bit melted. I recently replaced the alternator but could it overheat to the point of vapor lock?
I have seen failed head gaskets cause near zero coolant loss, yet cylinder pressure will over come the coolant system thus causing an air pocket that the water pump is incapable of pumping. Cranking the engine without the drive belt installed will quickly reveal a failed gasket or cylinder head. Blocks failing is truly an anomaly I have not seen on these motors, yet failed heads and gaskets are somewhat frequent.
In general white smoke exiting the exhaust is highly uncommon these and would require a major coolant leak to produce this type of result. Oil in the coolant would not likely cause an overheating condition because of the area the coolant is leaking into, this is also a fairly uncommon failure in my opinion.
swathdiver
Full Access Member
On other GM engines, I've had a head gasket failure that blew into the radiator but not the other way around.
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