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post #1 of (permalink) Old 10-01-2000, 06:15 PM
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Radiator problem

I have a 1984 GMC Jimmy with a 379 ci diesel. The coolant keeps going into the overflow bottle after the engine heats up, the temperture gage reeds about and stays around 200 degrees. I replaced the radiator cap and the thermostat and the temp gage peaked out. Then frustrated, I took the thermostat out and the temp is now down to around 125 degrees, but it still leaks out the overflow bottle.
Any advice would help and I hope it has happened to someone outthere and you can tell me how you fixed it.

Thanks Troy

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post #2 of (permalink) Old 10-02-2000, 02:04 AM
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Re: Radiator problem

i had a old 350 that did something simular like that . i thought was a bad head gasket.but turned out to be a cracked head

post #3 of (permalink) Old 10-02-2000, 01:38 PM
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Re: Radiator problem

Look in your radiator and see if there is any mixture of oil and water( they don't actually mix but you'll see some floating) this would indicate a head gasket or cracked block.Also sometimes they'll smoke more than ussual if it's a head gasket.

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post #4 of (permalink) Old 10-02-2000, 06:08 PM
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Re: Radiator problem

I havent seen any oil in the radiator or coolant in the oil. The radiator has a lot of pressure in it even after sitting over night. Could my problem possibly be a clooged radiator? Thanks for your input. Troy

post #5 of (permalink) Old 10-02-2000, 07:25 PM
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Re: Radiator problem

sounds to me i would ckeack the rings and heads for leaks.

If it has tits or tires it will give you trouble.
post #6 of (permalink) Old 10-02-2000, 07:36 PM
 
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Re: Radiator problem

<blockquote><font size=1>In reply to:</font><hr>

I have a 1984 GMC Jimmy with a 379 ci diesel. The coolant keeps going into the overflow bottle after the engine heats up, the temperature gage reeds about and stays around 200 degrees

<hr></blockquote>

Now I don't know about diesel's but 200 ain't all THAT bad, about 20 over ideal. As far as coolant going into the overflow, that's OK in fact that's why it's there!
I wouldn't worry about that unless its draining the rad and overflowing the overflow. I would say you may have some restriction somewhere[img]/wwwthreads_images/icons/frown.gif[/img]
<blockquote><font size=1>In reply to:</font><hr>

I replaced the radiator cap and the thermostat and the temp gage peaked out. Then frustrated, I took the thermostat out and the temp is now down to around 125 degrees, but it still leaks out the overflow bottle.

<hr></blockquote>

I have no idea what your level of mechanical skill is, so PLEASE don't be insulted! but this sounds like a text book case of putting the thermostat in upside down (don't laugh it's a hell of alot easier than most people think) especially when you say that by removing it your temp dropped to 125!

My advice is to put a new thermostat (like a 180) back in there, make sure it is in right (no offense intended[img]/wwwthreads_images/icons/wink.gif[/img]).
Flush the system with a Prestone or Zerex flush kit.
Refill it with a mix of distilled water, antifreeze, and maybe a bottle of waterwetter. Remember the more antifreeze in your mix the hotter it will run! (I believe you need at least 25%).
If it still runs hot after this, remove the radiator and have it rodded and pressure tested (should cost around $40).
If it STILL runs hot and severely overflows the overflow you probably do have a blown head gasket or a cracked/warped head .

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post #7 of (permalink) Old 10-02-2000, 07:36 PM
 
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Re: Radiator problem

this reply probably wont help ya any but I've got a 379 in my '86 and I've been having radiator problems for a while. Seems there is a small hole in the radiator but it doesn't leak out at a constant rate. Earlier during the summer when the temp outside was 100+ with the heat index the trucks temp would be fine(around 150) at 45 mph but as soon as sped up to highway speed(55-65mph) the trucks temp would climb almost instantly to around 200. I haven't let it go over 200 yet, when it would get that hot I would let off until it cooled down a bit. I was having to add a 1+ gallons of coolant every 50-60 miles. But since the weather has cooled down I haven't had as many problems. The truck hasn't got near 200 degrees in several weeks(been staying around 150) and I've been on the road a lot more than I was during the summer. It hasn't been using near as much coolant either. I know that a new radiator or getting the old one repaired would solve my coolant loss problem but nobody in my area has been able to tell me if fixing the hole woill cure my over heating problems. This problem has cuased me a lot of headache because I haven't been able to travel 30+miles without the fear of overheating in a long time. Maybe my post will help ya.

<font color=blue>86DIESEL[img]/wwwthreads_images/icons/wink.gif[/img]
'86 K10, 6.2 diesel, Jet T700, Flowmasters, BFG M/Ts</font color=blue>
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post #8 of (permalink) Old 10-02-2000, 07:59 PM
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Re: Radiator problem

Don't know if this will help or not, but: When I put the 400SB in my '92, it would pump fluid into the overflow, a little each time I started and stopped it warm. Eventually it would start overheating until, I refilled the radiator, and start the process all over again. I changed thermostats and caps. Even had the radiator cleaned and tested. No fix. Finally a radiator shop suggested trying a higher pressure cap. The factory cap was a 15 psi (I think) and I put an 18 psi cap on it. Fixed the problem.

post #9 of (permalink) Old 10-03-2000, 10:02 AM
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Re: Radiator problem

I would stay away from anything more than 15psi on the rad cap. The system is not designed to take that amount of pressure - you could cause other damage, especially to the heater core which is not fun or cheap to change. A properly working system shouldn't need more than 12lbs.

To the first guys problem, I would suspect either a small crack in the cylinder head or a probably a failed head gasket on #7 or #8, these are easily repairable.

To 86Diesel, check your injection timing, with no load your diesel shouldn't break a sweat. The clutch fan will kick in at about 210 degrees coolant temp (about 195 degrees air temp coming off the rad), that will drop the temp gauge real quick. Running down the highway at 55-65mph my 6.2L runs at 180, and unless I'm hauling 2000+lbs, it doesn't go over 200 until I hit an 8% grade. You might try advancing the injection timing (one line width max). I'd also make sure your air filter is good. Sounds like you need some attention to the rad in any case.

Hope this helps.

post #10 of (permalink) Old 10-03-2000, 11:15 AM
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Re: Radiator problem

Tmeier it wouldn't hurt for you to flush your radiator and your block and reverse flush both of them to,This wont cost you anything,keep doing it until the water runs clear both ways.

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