'87 302 overheating
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More Turbo
Joined: Jun 2004
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From: Sweden
'87 302 overheating
This '87 302 EFI has always managed heat well- in the "O" of NORMAL at most, even on desert highways.
Suddenly it's going up a lot- even outside the top of the whole NORMAL band (not just the letters).
Water pump and thermostat are around 4-5 yrs old, radiator's a couple of years old. I replaced the water temp sender just now to try to fix it, but the reading's still very high.
I was suspicious of the voltage regulator on the gauge head, but the oil pressure gauge doesn't vary with the water temp, and aren't they driven off the same voltage?
Since I ran through a lot of bugs a week ago, cleaning the radiator was the first thing I tried. I hosed most of the bugs out of the AC condenser in front. There are still some bent fins on the condenser but I don't think even the cleaning made a lot of difference. I'll get a radiator comb to straight it, but I think the problem lies elsewhere.
Is there something that could be wrong in the engine to make that much heat?
Any suggestions? I've got the voltage reg, thermostat, and fin straightening on the list. What should I try first?
Suddenly it's going up a lot- even outside the top of the whole NORMAL band (not just the letters).
Water pump and thermostat are around 4-5 yrs old, radiator's a couple of years old. I replaced the water temp sender just now to try to fix it, but the reading's still very high.
I was suspicious of the voltage regulator on the gauge head, but the oil pressure gauge doesn't vary with the water temp, and aren't they driven off the same voltage?
Since I ran through a lot of bugs a week ago, cleaning the radiator was the first thing I tried. I hosed most of the bugs out of the AC condenser in front. There are still some bent fins on the condenser but I don't think even the cleaning made a lot of difference. I'll get a radiator comb to straight it, but I think the problem lies elsewhere.
Is there something that could be wrong in the engine to make that much heat?
Any suggestions? I've got the voltage reg, thermostat, and fin straightening on the list. What should I try first?
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Joined: Apr 2001
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From: East TN
I had a problem with an '88 5.0 overheating, noticed that the previous owner, when he changed the water pump, he also changed the radiator cap to a 7lb. Changed back to a new 16lb and changed thermostat to a 180 degree from a 195 and now no overheating, temp gauge doesn't go over A. Also, was told to check the fan clutch as they are bad to go out and cause you temp problems when driving around town in stop and go.
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More Turbo
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From: Sweden
Well, they're good suggestions, but the cap pressure only controls the pressure at which the thing vents, right? I wasn't losing coolant so I don't think it's venting. And the thermostat's going to cut off the cooling below the set temp, it shouldn't affect coolant flow at higher temps.
The radiator itself is new, although I did peep in through the cap and I can see some deposits in there. But it's not plausible that it would cause a sudden change. There's still a problem in cooler night temps, though it looks lower- it's not like we're having a sudden heat wave here.
I'm wondering more and more if this isn't a gauge problem, but it does seem to respond to turning on the heater full blast (wow that's painful in Texas summer, but it works), and changes in air temp. That or some odd blockage in the coolant flow or thermostat. Just weird!
The radiator itself is new, although I did peep in through the cap and I can see some deposits in there. But it's not plausible that it would cause a sudden change. There's still a problem in cooler night temps, though it looks lower- it's not like we're having a sudden heat wave here.
I'm wondering more and more if this isn't a gauge problem, but it does seem to respond to turning on the heater full blast (wow that's painful in Texas summer, but it works), and changes in air temp. That or some odd blockage in the coolant flow or thermostat. Just weird!
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More Turbo
Joined: Jun 2004
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From: Sweden
Well, talking to the auto parts store guy who's got a lot of 302 experience, he sez thermostat. It was 4 or so yrs old and he said in Texas he recommends 1 yr.
I found this to be a very major job on this vehicle. I had to pull the serpentine belt and the AC compressor bracket. I started to remove the coolant hoses to get access to the bolts, but found it wasn't totally necessary, which is good cause I couldn't get them off. I'm not sure what the previous guys used for a gasket, it didn't look like the std paper nor did I recognize it as silicone. Hard, stuck strong to the metal, and didn't come off in one piece. It needed replacing, and my scraper did nothing to it! Spent over an hr with a flatblade working on it.
Anyways, I got it back together, ran it, and it dribbles right out! I don't get it. I used a new gasket (didn't use blue gasket silicone on top of it though), made sure I put the thermostat on the side with the lip. I tried to be sure the thermostat didn't slip past the lip and keeping the housing apart and I think I did that. I'm stumped... and waiting for it to cool down again.
I found this to be a very major job on this vehicle. I had to pull the serpentine belt and the AC compressor bracket. I started to remove the coolant hoses to get access to the bolts, but found it wasn't totally necessary, which is good cause I couldn't get them off. I'm not sure what the previous guys used for a gasket, it didn't look like the std paper nor did I recognize it as silicone. Hard, stuck strong to the metal, and didn't come off in one piece. It needed replacing, and my scraper did nothing to it! Spent over an hr with a flatblade working on it.
Anyways, I got it back together, ran it, and it dribbles right out! I don't get it. I used a new gasket (didn't use blue gasket silicone on top of it though), made sure I put the thermostat on the side with the lip. I tried to be sure the thermostat didn't slip past the lip and keeping the housing apart and I think I did that. I'm stumped... and waiting for it to cool down again.
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Joined: Aug 2004
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From: Dover,Arkansas
Man am I glad that i'm not the only one that had that problem My truckhad a alummimn thermsat housing that had a crack in it I put a new cast iron for about 9 bucks I put grey High temp on both sides of the gasket on my 1984 f-150 302 with a carb 2 barrel The housing/neck had a indention in it for the thermsat. So I put the gasket on the motor Han know I have no leaks
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From: Sweden
I found out that despite my efforts, the thermostat had dropped off the indentation. The gasket was so thick (and it was propping the underside apart) that it didn't show. When I took it apart again, the misalignment was clear. This time I removed the radiator hose from the housing so I could monitor and manipulate the thermostat through the opening. Bingo!
It's still a bit on the hot side- like the right on the "A". I didn't check the thermostat's temp as listed on the box. I already shot the pressure washer through the radiator to clean it. It's moved a bit higher at times, which looks like the thermostat's full open and it's still having some trouble despite the current moderate air temps. Still a bit concerned.
It's still a bit on the hot side- like the right on the "A". I didn't check the thermostat's temp as listed on the box. I already shot the pressure washer through the radiator to clean it. It's moved a bit higher at times, which looks like the thermostat's full open and it's still having some trouble despite the current moderate air temps. Still a bit concerned.
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Senior User
Joined: Aug 2004
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From: Waukesha, WI
Is there a way to check to see if the water pump is actually pumping. A friend of mine with a 93 Ranger had overheating problems, took his water pump off and all the blades for the impeller where gone. corroded away. Of course he found this after he replaced the radiator, sending units, had it in the shop, etc.
Brian
Brian
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Joined: Jan 2002
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From: Minnesota
When you put the thermostat in the outlet use some rtv silicone and let it cure and glue the thermostat in there. That way it will stay in place. I learned that the hard way and cracked my outlet when I tightend it.
If the radiator has some deposits in it that could cause it to be hot. The standard light duty radiators are pretty wimpy. There could be 2 reasons a newer radiator would become inefficient: 1)The coolant is old and lost its additives causing deposits or 2)Hard water will leave deposits. The water here has a lot of iron and calcium in it. I always use distilled water for all my vehicles cooling systems.
Good luck finding your problem.
If the radiator has some deposits in it that could cause it to be hot. The standard light duty radiators are pretty wimpy. There could be 2 reasons a newer radiator would become inefficient: 1)The coolant is old and lost its additives causing deposits or 2)Hard water will leave deposits. The water here has a lot of iron and calcium in it. I always use distilled water for all my vehicles cooling systems.
Good luck finding your problem.
