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1994 Dodge B150 Van Coolant Leak

On my way home from work, after driving about 45 minutes, I stopped at the Post Office. On the way out I noticed that coolant was leaking. I was able to make it home without overheating.

My guess was either the water pump or a hose. This morning I physically checked the hoses and they seemed fine. I filled the radiator with water and started the van and let it run until it got hot. I watched to see if I could tell where the leak came from. I could not get it to leak, after 15 minutes I gave up. I know it was leaking yesterday, not only did I see green coolant, the radiator was low on coolant.

What should I do to further diagnose the problem?

BTW, we love the show.

You won’t get Tom and Ray on this forum, just a bunch of mechanics, former mechanics, shadetree mechanics, or otherwise mechanically inclined or enthusiastic people.

That said, the first thing to do would be to pressure test the cooling system to identify the source of the leak. If you don’t have a pressure tester, you may be able to rent one from an auto parts store with the loan-a-tool program. You use a pump to pressurize the system to make it leak, then you can pinpoint the source of the leak and repair it. If I had to guess where your leak is coming from, I would guess either the water pump or bypass hose, since these are the most common coolant leaks on these vans as they age. Both are on the front of the engine and both are a few hour’s work to replace, and kind of a pain in the butt to deal with. I realize you said you checked the hoses, but the bypass hose is not visible without some disassembly.

Thanks. I will see if a friend of mine has the pump, if not I will head to AutoZone.

Engine access in vans can be a nightmare. But the first step is to remove the dog-house…If it’s the water pump, you must slide underneath and look up at the suspect pump…Decent lighting is a must…have fun…

Can’t I access the water pump by removing the cowling around the fan?

After a check of the radiator and hoses, I would strongly suspect the weep hole in the water pump. That would explain the on again off again aspect of it, plus you’ve got to get down there and look under the shaft of the pump so see the moisture.

I just did a water pump in one of these vans with a 318 in it. To get to the water pump, you do indeed remove the fan shroud. Removing the fan from the water pump can be tricky. I used an air hammer with a long chisel bit on the flat of the nut with the belt still on to knock it loose. The alternative is to use a spanner wrench and the correct size pump wrench (long, thin pattern wrench commonly seen in industrial settings). You may be able to rent these items at an auto parts store. The major tool companies (Snap-On, Matco, Mac) also make a specialty wrench set that uses interchangeable pump wrenches on an air hammer adapter that works like the long chisel setup I mentioned, but with greater success. That wrench set is pricey, though, like a couple hundred bucks or so, and only work with an air hammer.

One other thing, I am almost sure that the fan screws on BACKWARDS.In other words, to screw it off you must turn it clockwise.

I agree with Mark’s “good place to start”, as well as the other good commenst you’ve received. I just wanted to add that water pumps can, ehen they’re beginning to leak, leak intermittantly around the shaft seal. It is not at all uncommon.

sincere best on this one.

Thanks for the advice. I bought a water pump and bypass hose. I have the shroud taken off and fan exposed. I have the fan wrench set on loan from the local auto parts store.

How do I unfasten the fan? There is a large nut on the backside of the fan. Do I hold the fan and turn the wrench? Is is reverse threaded?

Thanks again.

While the water pump is likely the culprit, I wondered if you checked the obvious—was the coolant recovery jug full to the brim? If so, it may have overfilled and the coolant spilled out of the overflow tube. There are a number of reasons this can happen, but it’s what I’d check first before changing the water pump.

I think this fan is right hand thread, but cannot be 100% sure. I have done others since the last 318 water pump I did. To determine which way the nut needs to be unthreaded, bump the key or start the engine and observe which direction the fan is turning. If the fan is turning clockwise, you will need to turn the nut clockwise to remove the fan, and vice versa. You could also look at the pitch of the fan blades. When viewed from above, if they look like “/” the nut is right hand thread. If they look like “” the nut is left hand thread.

FYI, on my van the fan is normal threaded. I heated the nut with a torch. After it cooled sprayed it with PB Blaster. I had a friend hold a tire iron between two pulleys to keep the engine from turning. I removed the fan using a large pipe wrench.

Tomorrow, if I have time, I will finish the job.

Replaced the water pump and bypass hose. It still leaks.

It looks like the leak is coming from the bypass hose tube. I replaced the o-ring. My plan is to buy the tube and replace it. Is the tube a common source of a leak? Should I put a sealant around the outside of the tube?

The bypass tube is a common source of leaks, mostly when they get damaged during service. It can be very difficult to persuade them to leave their residence inside the water pump. Any auto parts store should stock this part, maybe even on the floor if they stock lots of Dorman Help! products. Do not use any sealant on the tube or o-ring. You can (and should), however, use dielectric grease or petroleum jelly on the o-ring before installing the tube to prevent it from shifting and causing a leak, or getting gouged and torn.

I don’t know why you are replacing parts when you haven’t pressure tested the system yet as Mark207 said.What is ypur next step if these doesn’t stop the leak? Radiator and head gaskets?

I do not have a pressure tester, and I need to get the van back on the road. The leak was coming from the water pump area, it is a 20 year old water pump, and so I took a chance.

The leak is not as bad as before I replaced the pump. So my guess it that the pump was bad, and I bent the tube wrestling to get it out of the old pump.

Besides, it was a good learning experience for my 12 year old son.