1978 FJ55 - Vintage AC added and now the engine runs hot.

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Long story short, but I have my Pig at a shop in the Dallas area and the guy says that according to his heat gun the engine is running 225 at the head with the AC on and 200 without it on. He has added an extra electric fan which has a helped a little at idle but not much effect at highway driving speeds. So he is suggesting that we recore the radiator "to a bigger size" to help.

What are your thoughts? Recore? different radiator altogether? Other alternatives?

thanks in advance,

M
 
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Do you have a shroud on radiator? Are there any restrictions in front of the grill/radiator? What about upgrading to a fan used on a model with AC?
 
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yes there is a shroud. nothing restricting the air flow in front of the radiator. I'll see if I can post a few pics. I don't know about upgrading the fan, I havent looked into that.
 
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Do you trust the infrared heat gun? A cheap infrared gun is not the tool for the job. Those tools provide an average temp of the area that your pointing it at, the accuracy is highly dependent upon the emissivity of the surface, and the area you're measuring. If he's measuring the temp on the exhaust side, then the value is 100% worthless. The cooling system in a 40 holds about 5 gallons of coolant, in other words, you've got a pretty large thermal reservoir to work with. It might be worth playing with some numbers to even see if the amount of heat removed at the condenser could raise your coolant temps by that amount. Just a dude pointing a gun at your engine and saying there's a delta T of 20* doesn't mean diddly.

Lets start with a more effective measurement. Can you put a K type thermocouple (for your multimeter) at the water neck and try to measure the temp there whilst driving an identical course on a hot day with air on and again with it off?
 
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Midland, TX
Do you trust the infrared heat gun? A cheap infrared gun is not the tool for the job. Those tools provide an average temp of the area that your pointing it at, the accuracy is highly dependent upon the emissivity of the surface, and the area you're measuring. If he's measuring the temp on the exhaust side, then the value is 100% worthless. The cooling system in a 40 holds about 5 gallons of coolant, in other words, you've got a pretty large thermal reservoir to work with. It might be worth playing with some numbers to even see if the amount of heat removed at the condenser could raise your coolant temps by that amount. Just a dude pointing a gun at your engine and saying there's a delta T of 20* doesn't mean diddly.

Lets start with a more effective measurement. Can you put a K type thermocouple (for your multimeter) at the water neck and try to measure the temp there whilst driving an identical course on a hot day with air on and again with it off?
I can't do any of that, the truck is 5 hours away in Dallas. This guy came highly recommended but I am fast losing confidence in his ability. I went ahead and gave the OK to recore the radiator as I'm sure it hasn't been done, ever.
 
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I can't do any of that, the truck is 5 hours away in Dallas. This guy came highly recommended but I am fast losing confidence in his ability. I went ahead and gave the OK to recore the radiator as I'm sure it hasn't been done, ever.
What are they charging for a re-core? A new oem rad is about $275. Could it solve your problems, maybe, but I'm doubtful you were that close to the cooling capacity threshold to cause your problems. Did a drive down the road change the measured temp? How did the temp gauge behave? Sounds like maybe your mechanic is fishing for work. I would definitely question his diagnosis.
 

Pighead

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Wasn't '78 the first year to offer AC in a Pig? And they had to slim down the radiator to fit (went from a 3 row core to a 2 row core).
You might be able to re-core to a modern (slimmer) 3 row core.
You're running the larger plastic fan aren't you?
 
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fjwagon

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There several things to look at in my opinion, make sure the hoses do not have corrosion at the neck where it's clamped. Make sure the thermostat opens and fluid starts moving. Make sure the waterpump does not have corroded fins. I had this issue. Always have the correct amount of oil. It does matter. I also had this issue as well. Engine runs a little hotter when a quart short. I have an oil cooler on mine. I even have a heat sink on the oil filter. This heat sink probably does not help but what the heck. The radiator issue was brought up and definitely worth replacing or recoring it. Personally i would replace it. Sometimes when you out of options it just may well be that you have tired engine. Make sure whatever they are using to check the temperature is calibrated. We use one made by Fluke. Good luck hope they can fix your issue.
 
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fjwagon

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Ask them if temp comes down if you run the heater while also running the A/C.
 

Pighead

Stop calling it an FJ
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Apparently not on a 78. Fan clutch started on a 55 with 1/79 production.
The 1/79 Pigs came with a fan clutch? I did not know that, i stand corrected.
I am a big fan of re-coring 55 radiators. I've done it 3 times on my Pig. I could never find a new one.
Find the oldest radiator shop in your town.
I think a good re-core is better than new.
Once i tried a 4-core that the shop said would fit, the tubes were thinner and smaller, as were the fins, but it worked. It was fragile and didn't last 10 years.
I went back to a sturdy 3-core that looks just like stock and have been very happy with it.
 

fjwagon

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I totally agree on the recore if you have the original radiator or if it's one of the older radiators that is not oem. They are not made like used to. As a 45 and 40 owner i have recored them but I've had better success replacing them. There are more vendors for fj40/45. You have to find the right shop. Sometimes they will cap the core because its too far gone but they don't know until they take apart and inspect it. I've had one where several cores capped at that point I just would weather replace it. I would rather do this than have warped head.....I've had that too. But recore if it looks like a good candidate or least save for later it if it's worth repairing.
 

WarDamnEagle

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The 1/79 Pigs came with a fan clutch? I did not know that, i stand corrected.
I am a big fan of re-coring 55 radiators. I've done it 3 times on my Pig. I could never find a new one.
Find the oldest radiator shop in your town.
I think a good re-core is better than new.
Once i tried a 4-core that the shop said would fit, the tubes were thinner and smaller, as were the fins, but it worked. It was fragile and didn't last 10 years.
I went back to a sturdy 3-core that looks just like stock and have been very happy with it.
So after re-coring, do they powder coat or paint the radiator? PO replaced the original radiator with an aluminum aftermarket but I want to eventually go back to the OEM radiator, which I got with the 55. It seems to be in pretty good shape but I would want to re-core it at a minimum before using it.
 

Pighead

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So after re-coring, do they powder coat or paint the radiator? PO replaced the original radiator with an aluminum aftermarket but I want to eventually go back to the OEM radiator, which I got with the 55. It seems to be in pretty good shape but I would want to re-core it at a minimum before using it.
Radiator shops, in my experience, always put a coat of gloss black rattle can on it just before you pick it up. So you can have some damp paint on your hands...
 

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