The battle that never ends...engine temps (1 Viewer)

2000UZJ

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Short of replacing the engine, it just doesn't seem to want to run cool. I have replaced everything that is related to the cooling system within the past 5 months. I thought it was normal for 100's to run hot. I've talked with many, many members and none of them are seeing temps anywhere near mine.

List of items replaced:
-Timing Belt
-Water Pump
-Thermostat
-Radiator Cap
-Radiator
-Coolant Flush
-Fan clutch
-Oil (2,500 miles per change)
-OEM Air Filter
(All parts are OEM)

Tempurates I am seeing are:
Idling: 205*F-230*F
Highway: 195*F-220*F
City: 205*F-250F*
Stop-Go traffic: 210*F-270*F
Crawling/Wheeling: 220*F-285*F (Major Issue)

I have to shift into neutral in traffic and hold the RPM's around 2,400 in order to pull air into the engine to keep the temps down. The time frame it takes the water temp to climb from 195*F to 220*F is roughly 2 minutes in standing traffic. I sometimes pop the hood and rely solely on the safety latch to allow more air to pass through the fender/hood gap in traffic. I have done a complete coolant flush, I am not loosing any coolant. Ambient temperature does have some factor in the temperatures. Summer time is much worse, average water temp hovers around 230*F. It seems that my truck requires a massive amount of air passing through it in order to cool properly. I'm not quite sure what is going on, however it's a bit frustrating when you have to stop every 2 miles on the trail to open the hood and build the revs to 3,000RPM to pull air into the engine and build fan speed to cool. The amount of heating/cooling/heating my engine is seeing makes me worry that the expansion and contraction may cause a premature failure of components.

I take this isn't normal. What might I be overlooking? What might be the problem?
 

snobdds

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If your not dumping back fluid back into the overflow, your not overheating. Is this happening? Is the sender good and reading an accurate temp?

I always do a coolant pressure test to make sure nothing weird is going on. It has detected for me hoses that crimp under pressure blocking flow and small leaks that release the pressure of the system. Are your hoses all good?

Beyond that...you've done everything I could think of.
 

2000UZJ

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I have not checked the temperate sensor. I have replaced all main coolant hoses.
 
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Have you replaced your AC condensor fan yet? I had one get gummed up with mud after playing around in some deep muddy water holes and my engine started running hot until I replaced it. I put a brand new one in (Bosch replacement IIRC) because I had high mileage and figured it was the original.
 
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Does the hvac work correctly? Ie, Is the thermostat working correctly.

Have you done the spin test on the fan clutch to make sure it is good.
 
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When I changed the radiator on my 60 it ran hot. I tried everything to "burp" the system (incline, hi-lift, etc.), it wasn't until I used a friend's tool that pulls vacuum on the whole coolant system that I got all the air out and it ran cool.
 

spressomon

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Mudded up/dirty radiator fins? Check both sides.

Mine, per Scan Gauge II, stays @ 183-186 typically. Crawling in hot weather with A/C on and ~ 4 tons GVW...it might hit 205.
 
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Bloomer

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^^^had this problem on a tractor where dust actually built up in the fins and restricted airflow across the radiator causing the engine to run much hotter. After a thorough rinsing, operating temp returned to normal. Hope it's something simple like this.
 
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Are all your radiator/fan shrouds in place? They are quite important to make sure the fan is actually pulling air through the radiator.

You seem to have done a thorough job on the cooling front. Have you checked out the exhaust side of the motor? Specifically have you checked for failing/clogged cats?

This may not solve your problem, but as a backup, you can resort to cranking up the cabin heater to help augment the cooling system. You might not be comfortable but it does actually work.
 
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Also agree with thoroughly washing all mud dirt debris out of radiator fins. The southern muddy clay and water sticks in there and it seems impossible to get rid of. I've grown to really hate the muddy wheelin but sometimes it's unavoidable. Clogged radiator and AC condenser fan shot from mud and water was the root of my problem running hot.
 

spressomon

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Hey Nick, maybe turning off your gajillion lumen LED's will help :D

And don't power wash the radiator with high pressure...gets the dirt/mud out but folds the fins over too ;)
 

serenity

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I'll add another voice to cleaning out radiator fins, the AC in my cruiser would blow hot when stopped at lights etc. but would blow cold at speed. On my cruiser I have an intercooler and tranny oil cooler up front, the AC condenser in the middle followed by the radiator. Cleaned all the dirt, dead bugs, grass and rocks out of the intercooler and tranny cooler and straightened as many fins as possible. I used some zip ties to basically rod out the fins all the way through, took a few hours and many beers.
Once I had done that the AC blew cold all the time even on 40*C days. I'm sure the tranny oil, engine coolant and intake temps benefited as well.
 
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third on the cooling fins.. mine was caked in mud - I had to physically remove the rad and spend a couple hours flushing and rinsing each fin. same symptoms you have. drove it through mud/water a few times on a wheeling trip, over the hood
 
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2000UZJ

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I will pull the radiator and inspect again. It's a brand new OEM radiator. My original was leaking, and clogged quite bad. When Onur and I did the timing belt, I spent almost 2 hours and flooded his front yard trying to get the original clean. I have never seen that much mud come out of something.

The fan clutch was just replaced as well. Is there a valve that might be sticking in the engine that directs coolant? Thermostat was replaced. the temps were normal today, but I didn't drive it that far. I will report back when and if I find anything this weekend.
 

spressomon

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Well if you haven't heated/cooled enough cycles since all your work (i.e. cooling system related) then I surmise you have a bubble that you need to bleed out. As someone above pointed out you should be getting some overflow in your over flow container...or if not then you need to add anti-freeze/water to the system.

To burp: Normally I just run the engine with the radiator cap removed...then when the air bubbles subside, usually when the running engine is coming up to temp but not as high as normal operating temp (~185-190 and when the upper radiator hose is hot hot), I reinstall the cap. Hasn't failed me yet.

Fan clutch might be an issue, new or not as there has been a purported batch of bad right out of the box OEM fan clutches of late. But this is easy enough to test: With hot engine (fully up to operating temp) shut the engine off and try to rotate the engine fan. If it rotates easily then you know you have a bad/ill performing fan clutch. If it rotates but with significant resistance then its probably OK.

When the engine is hot and running what's the temp of the upper and lower radiator hoses? Assuming you are using OEM hoses...therefore not a strange issue of hose collapse?

And ditto on checking/swapping out the engine coolant temp sensor...although mine is OEM original.

Edit add: I assume you've checked both sides of the block to be sure you don't have a seep/leak at the drain petcocks right? Rare for a freeze plug too...but given your cold weather maybe a good thing to check. When you did your coolant system flush you drained the block out via the engine petcocks right? Hopefully you saw a decent amount of coolant come out...
 
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I have always struggled burping mine- usually involving putting it up an incline and putting manual throttle up to 2000 rpm, waiting 10 min and massaging the upper rad hose. Mine bubble resulted in poor idle, didn't notice temp problems. The 100 is a tougher one to burp.


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