So....

My 3.0L V6 with about 130 000 miles is giving me problems. It began with a blown coolant hose....one that goes to the heater core. I replaced this hose, and now the motor has overheated once, and I even heard some detonation (pinging). I shut it down and had it towed home. The next time I started the truck up it idled very high?

I replaced the thermostat, because it was easy, inexpensive, and I've never changed one before, and wanted to give it a try. The truck is still overheating.

Here are the the facts:

1) when I squeeze the upper rad hose (where coolant flows into the rad) it is very very firm, and hot. So firm, that I can barely squeeze it. My repair manual says I should be able to squeeze it, let go, and hear coolant refilling it. I don't hear this happening. The manual says this is a sign of a bad water pump.

2) After about 4 minutes of running, the temp climbs very quickly, and it climbs into the hot zone, so I shut it down.

3) I checked the rad, and there seems to be no coolant in it. I topped it up with about a litre of coolant. This did not seem to help.

4) About 6 months ago, the heater fan stopped working. It was intermittent at first, then eventually stopped altogether. I haven't fixed this.

5) I have grabbed onto the water pump shaft (the one that is in the center of the fan) and attempted to wiggle it up and down to check for play. NO PLAY. The manual says if there is play than that could be a faulty water pump shaft.

6) Since I've owned the vehicle (2 years, about 30 000 miles) I have noticed that it goes through alot of coolant...about 1 litre every few thousand miles) There were never any signs of leaking.

7) My oil is not milky, so I'm hoping it is not head gasket related

So I'm thinking it is a clogged radiator or the water pump. ARE THERE ANY OTHER CHECKS OR TESTS I CAN DO TO NARROW IT DOWN FURTHER? Can I put a hose on the top of the rad, and open the drain on the bottom of the rad and see if there is flow from top to bottom?

Any help would be great!

It sounds like a blown head gasket to me.

You can test the radiator somewhat by removing the cap and opening the lower drain valve. IIRC, a healthy radiator should completely drain in about 1 minute.

Frank

I hate to tel you Bud ;but on the 3.0 the fan is attached to an idler.. not the water pump. You may have a bad radiator cap or a small hole in the cooling loop. The fluid will evaporate when the engine is up to operating temp. The easiest way to check is to use a cooling system pump. Remove the radiator cap when the engine is cold,pump it up to the normal operating pressure & look for the leak. There are 2 freeze plugs on the back of the engine covered by the bell housing. I found 1 on my engine that looked really nasty when I pulled it out for an engine swap.Usually coolant going into the combustion chamber results in steam from the exhaust all the time...you know, like when you make a short trip in the dead of winter. Good luck & let me know how this problem turns out. I hope this has been helpful.Low coolant doesn't always = blown head gasket.

but it will very soon.

Three tests at minimal expense. Compression test. Radiator pressure test (rent the tool at the auto parts store).

Dye test for exhaust products in the coolant. Lisle Tools kit to check for it for about $50. Buy at a good auto parts.

I've got $5 that says the radiator core is at least partially clogged, too. Time to rod it out or recore.

Fast Eddy has some sound advice & he may be right. I bought a raider from my father-in-law that had been setting under a pecan tree for 6 yrs. I had some issues w/ it & did some basic troubleshooting that didn't cost a lot of money & found there were simple answers to MY problems. Just don't go running around waving your hands in the air screaming "The sky is falling !!!" when you really aren't sure yet. <img src="/forums/images/graemlins/pfft.gif" alt="" />

As said, compression test and coolant system pressure test should do it.

My money is on the head gaskets.

I've owned several vehicles with well over 200,000 miles on them & have never had a head gasket problem with any of them.... Maybe we have better water in VA? Who knows ?

I've only seen one rare type of head gasket failure in a 6g72 with MLS headgaskets, but these composite ones suck!

MLS?

MLS = multi-layer steel..... which require a very fine machine surface on the heads and block to avoid leaking..... they're not for everyone unless you have a machine shop with much better than average results.

The reason I said the head gaskets may be blown is because the upper radiator hose is very tight and a heater hose ruptured - perhaps from steam, but also likely from combustion gas pressure. If the head gaskets haven't failed, they soon will as Eddy said.

What could cause the head gasket(s) to fail? Likely a clogged radiator - also as Eddy said.

All speculation until the diagnostic and forensic work is done.

3.0L engines blow head gaskets if the cooling sustem isn't kept in good condition - radiators and cooling fan clutches are the main culprits.

Composite factory gaskets are fine..... and preferred by me...... even with moderate amounts of forced induction.

Frank