1996 Dodge Ram B2500 - 5.9L Overheating

[Princeton Auto]

We have a '96 Ram Van B2500 with an overheating problem.

We installed a fan clutch at the customers request. He was sure that was the problem. So--New Fan Clutch, New Radiator last year, New Water Pump, Replaced Thermostat and now removed so no thermostat, Flushed entire system, checked radiator flow.

Engine temperature continues to rise to the Hot level over a period of about 30 minutes of driving. I have compared the gauge reading with the DataStream info to confirm hot engine. It does not cool down even with water being sprayed on the radiator. (it does actually cool slightly, but not to the normal zone. Still in the hot area)

No evidence of head gasket problem aside from the consistant climb in temp. to the hot zone.

Any ideas? Head gasket? Restirction in cooling system--internal engine?

[brianp87]

r u getting combustion gases in cooling system.

[Princeton Auto]

Not that can be detected. I would think that if it was combustion and the leak is to small to detect, the cooling system would be able to keep up and keep it cool. Especially without a thermostat and water on the radiator.

I'm thinking head gasket myself, but no evidence except for the over heat.

The cooling system in the past had been extremely neglected and RUSTY! But, over time, we have been able to get the system cleaned up so it no longer contaminates with rust. This is a long time customer.

Oh, and no water loss either.

[brianp87]

Is the vehicle really overheating or just the gauge? Is there good coolant flow? What about air blockage frotm the condenser? Id keep checking for a head issue also. I had a turbo vw that took a while to find the cracked block

[Princeton Auto]

As I stated before, I compared the gauge to the coolant temp sensor for the ECM and it corresponded with the gauge. So yes, it is running hot.

Also, as stated before, we have used water to try to cool the radiator, driven without AC operating, and yes, we see water flow (no thermostat).

Head gasket or crack somewhere is likely at this point, but I wanted to get some input and see what others suspect.

[nickscarcare]

Should be able to use a gas analyzer or a combustion gas detector to check for head gasket. I would be suspicious.

[Tim Martin]

Well, I am wondering what the actual degrees the coolant is when it seems to be overheating. The specs for that are that the thermostat starts to open at 195 and is fully open at 216.

Here is what we have done in the past already. First, remove the thermostat and drill a 1/8" hole just off to the side of the center probe. This allows a small amount of coolant to be circulating all the time. We also have switched coolant brand to CAT coolant which is more effective at removing heat than many other brands of coolant. I know some fellows will reject that idea but we have seen it work already.

The other thing is that this may be a lean running engine which will automatically drive coolant temp up. So you may want to check the O2 sensors, computer controls etc that control air/fuel ratios. Even though there is no check engine light to send you in that direction it is a situation we see at times of an overheat complaint.

[steven kiser]

is the a/c condenser cooling fins restricted?

[Tim Martin]

Do something if you can. If on your scan tool you can switch it to lab scope function, well, even if you can't, what are the sensor one oxygen sensor readings? Where are they at? I read the thread again and am more convinced than before that you got a cylinder or perhaps the whole engine running lean which makes for a hot running engine. I have seen this after owners have been the circle from one shop to another replacing this and that and it comes here and we discover a lean running engine. Rather easy to find but it makes heroes out of the ones that can diagnose the system. I seriously doubt that you have a head gasket or cracked engine part anywhere. Those 5.9's were pretty solid engines. By the way, weren;t these the ones that were notorious for the underside of the intake manifolds leaking vacuum? Best check it out.

[steven kiser]

possibly a lean issue, but i'm thinking a restriction of the air or coolant flow. situations like this always throw a curve ball because we assume it's not the obvious. treat this as if it came into your shop a virgin issue and hadn't been a dart board. if intake has been off (as mentioned above as being an issue) there may be a restriction in the crossover ports. there may be a wad of permatex in there blocking the flow. if you have a infa red temperature scanner see if the rear of the engine is hotter than the rear while it's on the road and the temp is climbing. you may be able to attain this by raising up the rpm's and letting it run in the shop. i have seen plugged cooling fins as well as cardboard between the condenser and radiator. if it was a lean issue i'm thinking that there would be a tell on the exhaust manifold. i think that when tim mentioned the intake issue he hit on something. the temp gun may hold the answer. you can see the temp going into the radiator, in the radiator, coming out of it, the engine as well as any hot or cold spots. while it's warming up how is the heat coming out of the heater vents. if it's weak it's another point towards the intake being plugged.

[mopwrforme]

put a radiator in it i have done a ton of them in b-vans there may be good flow but its only flowing threw the upper 1/2 of the radiator because the lower 1/2 is full of sediment. when you pull it ill bet it weights a ton. just a thought you can verify this with a temp gun start at the bottom and run it along the lower seam then work your way up do it in sections i bet youll find its mighty cold at the lower portions of the radiator

[ricmorin]

put a radiator in it i have done a ton of them in b-vans there may be good flow but its only flowing threw the upper 1/2 of the radiator because the lower 1/2 is full of sediment. when you pull it ill bet it weights a ton. just a thought you can verify this with a temp gun start at the bottom and run it along the lower seam then work your way up do it in sections i bet youll find its mighty cold at the lower portions of the radiator

Good call. I'm with you on this. The rusty history of this vehicle supports this theory.

[brianp87]

He said it had good coolant flow so id still dbl check for combustion gases

[Tim Martin]

Ahhhh. I still lean towards a lean running engine. I seen it too often. Even though I m not always right, I'm sitting back waiting for the verdict on this one.

[ricmorin]

He said it had good coolant flow so id still dbl check for combustion gases

True that, but if it only had good flow through half the radiator, that would explain the slow rise in temp. I've had a few head gaskets that didn't show well with the blue combustion tester, though. One 6.5 sitting in bay 6 right now with blown headgaskets.

[brianp87]

I agree Id dbl check everythign. Overheating probs can be easy or hard to diagnose

[a&mauto]

We had one of these with a partialy plugged cat. You would have never guessed by how well it ran. It took a while but eventually it would just keep getting hotter.

[jbadenoch]

how do you know coolant flows well? if bottom clogged, top will still flow good. I'm with steve, use temp gun

[brianp87]

how do you know coolant flows well? if bottom clogged, top will still flow good. I'm with steve, use temp gun

Exactly

[liljoe]

how do you know coolant flows well? if bottom clogged, top will still flow good. I'm with steve, use temp gun

I am trying to save up and buy me one of those FLIR cameras, you can get one for about $1500.00 now adays. Take a pic and see what is really going on.....