Van runs hot!

[aforstie]

I have a 99 that just started to run hot. The first time it happened it overheated while driving a very short distance. Since then I have not been able to get it to overheat on two test drives. The temperature shoots up at idle pretty fast when the A/C is on. The temperature does not drop when the heater is turned on, and it does NOT blow hot air. Both fans appear to be working. The temperature now drops when I start to drive the van. Two years ago I replace the intake manifold gaskets, replaced the thermostat, and had the system flushed. Any ideas?

Just as a side note the whole time I have owned the van I have noticed that the temp rises (pretty fast to 210) when you start to climb a hill or stop and idle for a while, and the drops (pretty fast to 160 or so). Is this common for this vehicle? Could it be related to the problem I am having now?

[89ltd]

is the coolant filled up in the over flow tank? I would check in the over flow for air bubbles while it is running. My brother's 97 was doing the same thing , it was the head gasket at #2 cyl in the front.

[aforstie]

The overflow tank is full and when the van gets hot I can see some very small bubbles in the overflow. How would I further diagnose the problem so I know that it is a head gasket and not just air in the system?

[DRW1000]

Originally Posted by aforstie

The overflow tank is full and when the van gets hot I can see some very small bubbles in the overflow. How would I further diagnose the problem so I know that it is a head gasket and not just air in the system?

You might consider a compression test to check for a faulty head gasket.

I am bothered by the heater not producing heat. This can indicate a blockage somewhere. Your coolant is obviously heating up so you should feel heat. You of course have a separate issue with the heating system by don't ignore the possible link to the overheating issue.

[89ltd]

what happened with my brother's 97 venture was, it would over heat almost right away. I did notice a good stream of bubbles coming in to the overflow tank from the rad. What happened in his case was air from the combustion chambers was being forced into the cooling system and actually filliing up the over flow tank until it would over flow on the ground. There for, the van was low on coolant and thus no heat from the heater. The check engine light came on, then would also flash. He took it in, as I didn't have my code reader yet and they told him it was coming up with a "missfire on #2 cylinder" and also that it was a serious missfire(because check engine light was flashing). They took out #2 spark plug and it was covered with antifreeze, confirming either a cracked head, block, and or head gasket and quoted him $1500 to $2000 ball park, depending on wether the heads needed to be machined or not. They charged him $120 to check it and everything pointed to the head gasket so they didn't see the point of spending more money on a compression check. He has the 3.4 L engine, before I took it apart I let it cool and filled up the rad with fluid, let it warm up, burbed the air out of BOTH air bleeding spots, although the overflow was full, it took well over a gallon of fluid, then, the heater would work, but it would leak down the engine block from the #2 cyl. I'm not saying you have a blown head gasket, just trying to fill you in on the symptoms. I don't know what they would charge for a compression check(keep in mind how hard it is to get to the rear 3 spark plugs.) They could also pressure check the coolant through the rad to see if there are any leaks, need more info, let me know.

[89ltd]

may also want to check the oil for the pressence of anti freeze, looks a light brown milkshakish type thing, and check that the oil level is not up a quart or two.

[89ltd]

when I say air bubbles in the over flow tank, I'm talking about a good steady stream of 1/4" bubbles coming up from the bottom of the overflow tank where the small rubber hose hooks on from the rad....

[89ltd]

while the engine is running an up to temperature......

[aforstie]

Thanks to ALL for the great information!

I bled the system by taking off the two bleeder valves and it took about 15 seconds before water came out of both valves. In the process of doing that I noticed extreme amounts of sludge in the over flow and around the radiator cap. So much that I am convinced that the full flush I paid for two years ago was never done.

The oil and water (aside from the sludge) appear normal so I am pretty sure that it is not a head gasket. Bleeding the system and doing a simple flush just sticking a hose in the radiator while it was running seemed to help a considerable amount, but the problem is still persistent to some degree, and still no hot air from the heater. This leads me to believe that the system needs a complete flush. Is this something that is best to have done by a shop, or is it fairly simple to do? Or, based on what I have written, any other theories on what could be wrong.

Thanks in advance!

[DRW1000]

It is generally an easy DYI project..................for anyone that does their own oil changes, brakes etc...a $20 Haynes Manual can inform you of what is involved. It shouldn't cost too much in labour either but "if you want a job done right you do it yourself". Either that or pick a shop that lets you watch what is going on. A lot of stuff can build up in 2 years however, so don't assume they didn't do a proper job. I don't know specifically what sort of "sludge" you have but 2 year intervals for cooling system service is reasonable even with "5 year" coolant

Of course another question perhaps is why did you have air in the system? You may be low on coolant..Check level when cold.

One way or another a cooling system flush is a good step.

[aforstie]

A full flush is for sure in the near future. One more symptom that my wife just told me about was that the A/C smells like "vinegar". She told me this last week before all this happened and then she noticed it again today. I suspect that "vinegar" smell is actually coolant. Does this sound familiar?