Overheating/coolant issue...need some help
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Mountain Pass
Joined: Oct 2014
Posts: 181
Likes: 2
Overheating/coolant issue...need some help
I have a 94 F150 4wd 5.0 with only 90k miles and the truck has ran fine for the year that Ive owned it. The other day i noticed temp gauge creeping up. It would climb a bit, come back down, climb back up. It never really overheated as it never climbed past 3/4 of the way to hot. So i went home and the radiator was either dry or very low. However, the reservoir tank was still topped off. Anyway, so i filled ithe radiator with coolant and burped it through the system. I started the truck with the radiator cap off and it started spitting coolant. I shut it off immediately cuz i dont think this is normal. Im hoping i dont have a blown head gasket. What do you guys think? Whats the first place to start troubleshooting?
5th Wheeling
Joined: Feb 2012
Posts: 45
Likes: 1
From: Snow Camp, NC
I had the last motor in my 92 idi start doing this and it was a head gasket going.
I imagine it also could have been trapped air expanding in your case since you had just refilled the radiator.
I've also had coolant vanish due to a bad radiator cap which is a good place to start since your reservoir was still full. If I understand correctly a good cap will cause the system to draw out of the tank when it needs it.
Does the exhaust smell funny?
Keep a check on it over the next day or so. If it sucks down a bunch of coolant you have a problem.
Your wonky acting gauge is due to the sender not being constantly submerged in coolant because of the low level. It might have overheated but the sender wasn't reading it. I lost a motor because it busted a coolant hose while I was running in water. The coolant ran out, gauge stayed at a cool reading because of not having any coolant to read.
I imagine it also could have been trapped air expanding in your case since you had just refilled the radiator.
I've also had coolant vanish due to a bad radiator cap which is a good place to start since your reservoir was still full. If I understand correctly a good cap will cause the system to draw out of the tank when it needs it.
Does the exhaust smell funny?
Keep a check on it over the next day or so. If it sucks down a bunch of coolant you have a problem.
Your wonky acting gauge is due to the sender not being constantly submerged in coolant because of the low level. It might have overheated but the sender wasn't reading it. I lost a motor because it busted a coolant hose while I was running in water. The coolant ran out, gauge stayed at a cool reading because of not having any coolant to read.
Thread Starter
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Mountain Pass
Joined: Oct 2014
Posts: 181
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Thanks for the help. To respond, if this could possible be air trapped, should I drain all the coolant and refill? I havent smelled the exhaust but I will go check it in a few. I dont see any water or milky substance in the oil.
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Mountain Pass
Joined: Oct 2014
Posts: 181
Likes: 2
When you say burp it, can I accomplish this by squeezing the upper radiator hose? I did that after I filled it with coolant to begin pumping it through the system. If not, how do I burp it? I figured flushing the system would get rid of any air in the system
Logistics Pro
Joined: Mar 2011
Posts: 4,197
Likes: 558
From: Central Wisconsin
I suspect the radiator cap going bad, and not keeping pressure to the system. That would explain the loss of coolant, and possibly the fluctuating temp gauge. Sometimes thermostats will cause the gauge to fluctuate when they are going bad also. They don't open and close at the right temps, so the gauge creeps up and down.
Thread Starter
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Mountain Pass
Joined: Oct 2014
Posts: 181
Likes: 2
I suspect the radiator cap going bad, and not keeping pressure to the system. That would explain the loss of coolant, and possibly the fluctuating temp gauge. Sometimes thermostats will cause the gauge to fluctuate when they are going bad also. They don't open and close at the right temps, so the gauge creeps up and down.
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More Turbo
Joined: Mar 2006
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One thing that can help with a problem like this is one of those lever vent caps. Run to temperature, lift the lever to discharge into the overflow, let it cool and draw the coolant from the overflow and make sure it does by checking the level and repeat a couple of times. You may have to add coolant to the overflow
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Thread Starter
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Mountain Pass
Joined: Oct 2014
Posts: 181
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Ok I just looked up how to burp the system. The only problem is that when I start the engine with the radiator cap off, the coolant doesnt just bubble out of the neck...it actually sprays out all over the engine bay. Is this air escaping the system or is there another issue?
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Mountain Pass
Joined: Oct 2014
Posts: 181
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No the engine was cold. Ok here is an update: the coolant stopped spitting out of the radiator neck. The temp looks good on the gauge. With the radiator cap still off, the coolant level is rising and overflowing out of the radiator neck. Is this normal? I am catching most of it, but it keeps overflowing. Is this normal? Also, the heat is still on full blast if that helps.
Postmaster
Joined: Nov 2011
Posts: 3,533
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From: SW Florida
Ok I just looked up how to burp the system. The only problem is that when I start the engine with the radiator cap off, the coolant doesnt just bubble out of the neck...it actually sprays out all over the engine bay. Is this air escaping the system or is there another issue?
Thread Starter
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Mountain Pass
Joined: Oct 2014
Posts: 181
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What, like a volcano? Shouldn't be that dramatic. I'd fill it with water and see if it ever settles down. If so then drain it out and put in the correct coolant/water mix. But for reference I ain't ever had any engine spray it's coolant "all over the engine bay" just by having the radiator cap off. Might have a bigger problem, so here's hoping you don't!
More Turbo
Joined: Mar 2006
Posts: 687
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Put your cap on and start watching how much fluid you get in your overflow. Let it bubble into there some. make sure you have fluid in the overflow and let the system cool overnight and see if it draws fluid back into the radiator. Iv your system has no leaks it should draw some up. check the overflow tomorrow. If it is below the cold fill line add some. check your radiator that first time too if there is fluid near the fill neck put the cap back on and let it run to warm and it should burp into the overflow each time. Leave the cap on for the next couple of cool cycles. Your overflow will fill and burp your system. That is how I do mine.