All winter I've had a plow on the truck and the temp gauge would fluctuate from 1/4 to almost 3/4, which I wasn't happy about. All I've read pointed to restricted airflow with having the plow attached, especially since it was an 8' wide C plow. The truck did overheat on one occasion, so I replaced the rad cap and it was back to normal with the temp gauge fluctuating back and forth. I did take the plow off today and will see if the fluctuation continues, but my main concern now is the upper rad hose.

The upper rad hose has never had any pressure buildup. It always feels soft and when I squeeze it antifreeze moves back and forth in the overflow box even with the truck running and up to operating temp. Since it never builds pressure I'm thinking it might be the thermostat, but before I go through the trouble of changing it, I wanted to hear from others. The thermostat isn't expensive, but on this truck (1995 Ram 2500 gas V10), it's a bit difficult to get to.

 

I think my thermostat was north of 30 bucks....... I am used to paying less than 10. (sometimes, less than 5.....)

If you aren't building pressure, you have a leak somewhere. Need to find that first. It is supposed to be a closed system, if it isn't, then it doesn't work as you would expect.

 

So far I haven't seen any leaks and the overflow box still is holding the same amount of antifreeze, so I'm not sure a leak is the problem. For the upper hose not to get hard at all, I would assume if it was a leak, it would be a substantial one whereas I would be adding antifreeze quite often. Other than the one time it overheated, I never added any antifreeze all winter.

 

Sounds like the cap isn't holding pressure.

 

That's what I assumed and installed a new one I got from NAPA, but now that I'm thinking about it, there is the possibility the new one may be bad or the wrong part. It's the correct pressure, but it doesn't seem that it hits the bottom of the rad mouth to close off when it should. I think I'll pick up another one since they're inexpensive and see. I'll update with the results.

 

Does anyone know or have heard about the following information? I got it off an Autozone site under one of the comments. I'm wondering if this may be my problem with the rad cap:

So after getting this cap as a replacement, i learned about the difference between a "Full Pressure" cap and a "Partial Pressure" cap. If you research dodge/chrysler you will learn they need a partial pressure cap and not a full pressure cap. This cap is a full pressure cap. Whats the difference you ask? The bottom valve that operates under vacuum on the cap either has a spring which retracts it or it hangs freely. If you buy this cap you will have vacuum issues and your coolant will overboil and pop hoses and/or overflow like CRAZY out of the overflow.

 

Chrysler used the partial pressure caps (free hanging coolant return valve) up until the early 90s, when the switched to the full pressure caps. (return valve held closed by a spring.) Parts store should be able to tell you which one you should use.

 

Heck when I ask for spark plugs they HAVE to know the trim level or they can't help. Like different trims got different plugs . So you can't always trust the parts store

 

I go to a higher quality parts store. The guys at the advance auto here in town, actually have a clue. (and no, they didn't get them at Wal-Mart. )

 

Sadly around here that isn't the case. My buddy applied there and he's ASE certified they gave the job to a 67 year old lady... If you go in for a wheel bearing and you don't know mechanics they'll give you a driveshaft. Also if the computer doesn't list it or if they can't find it they don't carry it when you know they do.