We have a 2001 Ram 1500 4x4 with the 5.2L V8 engine, VIN 1B7HF16Y21S144711. Manual transmission. We use it on the farm, mostly for short trips from barn to field. High mileage, around 160000 miles. I'm not sure exactly when this problem began, but earlier this week, our employee reported that he thought the transmission was going bad, because he heard a chattering noise coming from below. He also reported a leak between the engine and transmission.

I took it for a short test drive through the fields, and was not able to duplicate the noise that he reported. The transmission seemed fine. However, following this initial test drive, I did confirm a leak below, where the rear of the engine block meets the bell housing of the transmission. I looked at the fluid and smelled it, and it was clearly not engine oil.

So I decided that it might be transmission oil, and removed the filler plug on the tranny, and found that the fluid level in the transmission was normal. I was stumped.

So I took it for another test drive, this time longer. After about 5 minutes of driving, I noticed a light chattering noise from below, under load, what I thought might be loose rod or crank bearings. Considering the age of the truck, and mileage, and also the severity of the noise, this didn't bother me too much. But then the "check gauges" light came on. I immediately saw that the engine was running at a VERY high temperature, close to 260, the RED line....I turned off the engine at my first opportunity.

I opened the hood. I found the radiator was cool, and was able to remove the cap without any trouble. The radiator was empty or nearly so. I went to get a bucket of water to refill the radiator. Upon refilling, I found that the fluid after a short while was pouring out of the space between the bell housing and engine block, almost as fast as I poured it in!

I managed to drive the truck 5 miles to our mechanic without overheating, who indicated it might be a heater hose. I was not able to see where the leak was coming from. The heater hoses appeared sound.

Our mechanic reported that he thought the problem was with the "frost plugs" at the rear of the engine block corroding and giving way under pressure of the cooling system. He had attempted to seal the leak with some sort of bottled substance, and it did apparently work for a little while, but as soon as the cooling system developed pressure, the seal gave way.

Unfortunately, he reported that the only way to fix the problem was to either remove the engine or remove the transmission, as the repair must be made by accessing the space between the two.

My purpose in posting is to enquire of several things: Is this a reasonably likely diagnosis? Why might this have happened? What is the purpose of a frost plug? Why would it fail at such a critical location? Has this ever happened to any of you? Is it indicative of other problem? Are there any alternative repair scenarios that wouldn't involve removal of the radiator? If we end up removing the transmission, is there any particular preventative maintenance that we should perform at the same time? Clutch replacement? Could excessive pressure buildup in the cooling system have caused the problem? And, finally, should I do it? The mechanic estimated the repair at around $800, without clutch replacement, which at this point we haven't even discussed.

I'd be very interested for feedback on this post. Thanks.

 

The purpose of freeze plugs is to pop out of the block if the coolant freezes to prevent cracking the block. Freeze plugs can eventually corrode and leak, that's just the way it goes. Leaking coolant on the clutch may be the cause of the chattering too.

 

i was thinking also the freeze plug itself may be rattling around in the bell housing

 

Makes sense. Thanks for the explanation. I guess the freeze plugs need to be soft/thin enough so that they would burst first in the event of a freezing block. Seems a shame though that they couldn't be made out of a non-corrosive material, though. Like you said, that's the way it goes.

 

If the freeze plug was missing you'd have a massive coolant leak.

 

just thought cuz he said it was pouring out between block and bell housing. besides that ive never heard of those cooroding in there only the one alonh the eges of block or on heads

 

Hahns,

That sound like it. The water was pouring out the back of the engine just about as fast as I was pouring it in.

Al

 

possible you hade a minor coolant leak and then it ran out causing the motor to over heat and pop a head gasket...

 

Here's a leaking freeze plug...

 

well needless to say he knows what the prob is now he just needs to fix it and there r 2 ways i would pull the tranny befor the engine less s*** to disconnect. but for &800 dollars i would tell that guy to pound mudd. and do it myself but if you dont have the means of doing it then i guess he is your option