So a konth ago I installed an electric fan and had a few bugs that caused overheating on a regular basis. Thought I had this licked but twice now in two weeks the engine overheats out of the blue. Today the temp outside was around 50 degrees and I was doing 50 mph and smelled antifreeze. Looked down and temp guage read about 250.
The fan is working correctly. I've received recommendations to replace the thermostat (possibly sticking partially closed) and the upper radiator hose (my brother says it feels too thin and he thinks it is collapsing.
The overheatin has no rhyme or reason. Comes out of the blue with the fan on and OAT less than 60 degrees. Upper hose is under pressure from water pump, so I don't see it collapsing from pump suction. Lower hose is reinforced internally with metal spring, so I don't see it collapsing. Stuck thermostat I would think would stay stuck closed, not open up fully for 20 miles and then shut itself off.
I bought a new thermostat to install when the weather cooperates. Changing out the 195 degree for a 180 degree. Bought the upper hose, but I think that is a waste of $$. Any other ideas?
First stay with the 195* thermostat. Are you still using the probe style thermostat for the fan? I had the same issues until I went with Flex a Lite VSC. It goes inside the top hose have not had a single issue with overheating. Do have grill inserts, winch or lights impeding air flow? Does the electric fan have a full shroud?
No way I could shell out $200 + for a fan controller right now. Yes, installed grill inserts and have a winch, but the electric fan is Hayden's largest and I can turn it off, let the temp get up to 220, then turn it on and it will cool down to 210 in 30 seconds.
The stock fan shroud is in place. And when in "auto" mode the fan kicks on low speed @ 210 degrees just as it should, if the engine gets up to 220 it goes into high speed as advertised. So I've eliminated the controller/temp probe from my list of suspects.
Why not go with the cooler tstat? Will 15 degrees make that much difference?
The engine was designed for a certain temp stay with the 195*.
Does the fan have a shroud? That is crucial for proper air pull through the radiator!
If you hold a piece of paper toweling 2 ft in front of jeep will the fan suck it into the grill? Regarding the VSC, you can find it cheaper elsewhere. eBay for one and you'll need the thread in line hose adapter too. https://www.flex-a-lite.com/1-3-4-inch-in-line-hose-adapter.html
Look at this on eBay:
The electric fan is rated at 1800 CFM through the radiator (2100 CFM free flow). Stock fan shroud in place. Neither stock fan nor electric fan would pass that paper towel test. Engine will idle for 30 minutes without overheating, the new fan is working. I suspect some issue in the cooling system that was being masked because the stock fan was pulling massive air. I'm stumped.
I looked at the flexlite fans on their web site, thanks for the link. They're pretty pricey. Don't understand how they are pulling double the CFM as mine with less amperage... defies the laws of physics.
My fan does pass that test. I'd go to car wash and gently clean radiator out. Remove the inserts at least until you figure this out. Does the fan and shroud fit snug? Radiator cap is good and 18#? Have you done a full flush? I know this is frustrating hope you figure it out.
Agree with removing the inserts as part of the troubleshooting. The fan fits fairly close to the stock shroud, but not snug making me think that maybe the area outside of the fan blade coverage is not getting any air flow, leaving me with about 30% reduction in cooled coverage.
That was my first suspect as well. It "felt" okay, but I changed it out anyway. Did not fix the problem.
If I had not inspected the hoses myself I would almost guarantee that a collapsing bottom hose was the issue, but you can't squeeze any of it together due to the wire reinforcement. The top hose feels normal to me, but as I have already bought one I'll change it and the thermostat out at the same time this week. I guess it would be possible for top hose to collapse, but I sure don't see it happening.
I believe the top hose is the pump discharge. No way for it to collapse. If the spring is rusting in the bottom one, it could be collapsing. Would be more prevalent at higher RPMs( pump is spinning faster) even a bad section of spring could cause part to collapse.
I've seen rad caps bad or of the box. See if you can get ahold of a tester and test it. Should hold pressure up until 18is lb then release it above it. My old cap wouldn't hold pressure at all.
At speed you don't need the fan at all, the jeep at 50mph is pushing more air through the rad then the fan could ever hope to.
If you know the cap is good, and you know the thermostat is good, burp the system, and possibly pull the water pump to check the impeller. They really isn't much else to go wrong.
Can also look into a cooling system flush. Could have some crud in the cooling passages.
Just my 2¢ but I've seen a couple Jeeps with worn to nothing vanes on the water pump. One of them ran fine except no heat. Pulled it apart and the impeller was gone. Is there a lot of rusty sediment in your coolant?
The coolant looks fine, and through the radiator neck the radiator looks pretty clean.
This is a perplexing problem in that it happens randomly, with little warning, at cool outside air temperatures with the electric fan running. No definitive variables to give me a clue.
Too cold to change out the tstat today and the Jeep is not my DD so I'll give it a rest until tomorrow and hope for better weather.
had this experience with mine. the engine ran fine but overheated after about 15-20 min at normal temp. flushed twice, changed tstat and wp, but nothing. popped the rad cap when cold, started 'er up and coolant would just come out.
gave in after being on foot for a week and tore the top half down, sure enough there was a crack between cylinder head 3 and 4 combustion chamber near the coolant duct. guessing coolant wasn't leaking into cylinder but exhaust was getting into coolant system...annoying as kcuf because the symptoms didn't add up to what i found
I had no issues until I installed the electric fan, and due to a bad ground the fan would operate intermittedly so it overheated a couple of times, but never what I would consider damaging (always shut down immediatly). Do you think running hot a couple of times was enough to crack a head? I sure hope not. I ran the engine with the cap off the other day, no bubbles in the coolant.
Changed out the tstat this afternoon, went really quick and easy. Did not change the upper hose, old one seemed not so old, definitely not $18 old.
The old tstat seemed to have a "flat spot" on it... I could push down on the spring and about 1/16" down it would catch before going further, so maybe that was the issue. I drove it to the local O'Reilly's to get a new petock for the radiator as it would not stop dripping and it did not overheat a bit. The store is only 8 miles away so it wasn't much of a test run, but for now it looks better. Oh, and that was with only 10% antifreeze, as I still have to flush and refill.
I am also thinking that the OP had 100% antifreeze, as what I drained seemed "thick". Could that cause temporary overheating?
If sucessful, the real test will be in the coming summer in 105 degree Arkansas heat.
Absolutely! 100% Antifreeze is NOT good for cooling. FULL FLUSH ASAP!!!
See below:
It is only when pure antifreeze-coolant is mixed with water that its freezing point is lowered. So if you need protection below the zero mark, you had best mix the antifreeze with water in the proportions suggested by either the car or antifreeze manufacturer. Playing guessing games or trying to alter the manufacturer's suggested proportions only will harm your car.
The second reason is the flip side of the first one. Pure antifreeze-coolant doesn't have the heat-transfer abilities that a mixture of antifreeze-coolant and water does. In fact, if pure antifreeze-coolant is used in a car's cooling system, the system loses about 35 percent of the heat-transfer capabilities it otherwise would have when antifreeze is mixed with the proper amount of water....
100% = poor heat transfer. Water is best for heat transfer, but the coolant is a lubricator, anti-boil and reduces freeze point)
50/50 is great in temperate climates
Max of 70% in very cold climates, but that means less heat transferred during hot months.
I don't usually see lees than + 10 F and run about 55%
100% = poor heat transfer. Water is best for heat transfer, but the coolant is a lubricator, anti-boil and reduces freeze point)
50/50 is great in temperate climates
Max of 70% in very cold climates, but that means less heat transferred during hot months.
I don't usually see lees than + 10 F and run about 55%
I did some research while Arkansas was kicking the Longhorns around thd ballfield tonight and confirmed the two posts above. Here is what happened:
1. Previous owner put 100% antifreeze in system. OEM clutch fan pulled enough air through radiator to keep it cool anyway.
2. I installed an electric fan that pulls in enough air to cool a normal 50/50 mix, but with 100% antifreeze the heat buildup with less airflow caused the system to flash over at random intervals. Had there been a small difference in the equation (more water or more airflow) I would have never known.
I tested the antifreeze, but only the freezing point. I don't have a method to check dilution percent.
So tomorrow I'll drain, flush and fill and put this thread to bed. Thanks for all the comments and advice!
I replaced everything trying to track down an over heating issue. Rad, fan, clutch, tstat, waterpump, cap. still over heated.... ended up being a clogged cat. replaced cat and no more overheating.
A few weeks back I discovered that the previous owner had 100% antifreeze installed, so I drained and filled with a 509/50 mix. Problem solved??? I thought so, drove for a week with no issues except a constant drip from the petcock. So I twisted it tighter, it leaked more, I put pipe tape on the threads, that seemed to stop the leak. Wife drove it and it overheated again. When I checked it out, it was low on antifreeze and the drip was now faster and steady. More tape on the threads but it did not help at all.
I ordered a replacement petcock, the wrong one came in. The right one came in yesterday and I went to install it today after work.
Getting the old one out did not go too well. I got a couple of pieces of it out before the rest of it fell into the radiator. Could not fish it out. I pulled the lower hose off and flushed but it still did come out. I refilled the system again, ran it down the road to replicate what happened to the wife, and while it did not overheat it did run hot. Apparently the adjustment screw on controller for the electric fan I installed a couple of months ago had backed itself out. Adjusted again, no drips, no overheating (but I'm holding my breath until warm weather arrives).
Two questions:
1) Am I asking for trouble by not finding the little piece of plastic that fell into the radiator? Will it pass through the system and lodge in the upper half of the radiator?
2) How much is enough when it comes to water pump output? I pulled the upper hose off the radiator, ran the engine until warm to check pump output. It didn't come shooting out like I expected but definitely was coming out and changed volume with engine RPM. Maybe I was expecting too much?
I don't have anything significant to add. I just wanted to say how glad I was to see that someone else enjoys my luck with trying to diagnose/fix things. I really love the intermittent problems...those are the best. Best of luck to you!
One other thing worth mentioning... when I was refilling the radiator and had the engine running to work out the air bubbles, before it got warm I noticed what appeared to be a wisp of white smoke floating out of the fill neck. But that was all - one little wisp. I hope it doesn't mean a possible cracked head. The Jeep runs perfectly, idles smooth and is pulling 20hg vaccum at idle.
Nice man. My overheating problems seem to be resolved, as well. Summer will be the true test.
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