94 X 4x4 overheats when worked hard

[Happy Jack]

Took it to the shop again this mornin and the guy asked if I researched this so I figured I'd post. Gonna be a little long. Bought it 3 years ago north of philly and it was a Jersey truck. Had the original one core radiator and M5OD in it. AC did not work and I drove it back to KS. Fixed ac and had the cooling system cleaned with BG product. Installed 2" lift, changed axles from 3.27 to 3.73 and added a rear locker. Warn grill guard and 9500i winch. Always had trouble running warm with the ac on. When the M5 went bad I installed a c-5 and T&M Doubler and went to 33 10.5 tires. I installed a new 2 core radiator. Had lots of issues with tranny heat and had it replaced with another c-5 (both were rebuilt but by different shops). Still problems with tranny heat and had the radiator bust and mix atf with coolant. Replace the radiator with newer 2 core auto one. Took the auto and doubler out and went back with the original M5 after a local rebuild. Droped back to 31" tires Has new radiator, water pump, thermostat, fan, fan shroud, fan clutch.

What it's doing is running hot enough to cook the hood (paint starting to orange peal) and vapor lock when push hard or long enough. Worse with the AC on. Last month went to Colorado to camp and wheel. Loaded it heavy with gear and stuff and headed west. Ran fine in the morning. In the afternoon when it got hot and I started climbing the temp needle started climbing. Started to smell a strong caustic gas oder. This had happened before on a trail with a very long steep climb and is usually followed by hard starting if I shut if off. Have had the smell soo strong it burns my eyes and throat and make folks sick. I needed to stop so I turn the ac off before I arrived at the next town. Sign in the previous town had said temp was 103 degrees. Cooled it down to 1/2 way. It vapor locked and would not start. Happens sometimes on the trail when I smell the bad gas smell and turn it off. It will start rough missing and sputtering. I run the rpms up to 1200 and after a while it clears out or if I parked it facing down hill just start down the hill in gear and suck cooler air through the engine. This time it would not go up to 1200 or clear out. Opened the hood and let it cool down for 1/2 hour or so and it started rough and went to 1200 and cleared out. I continued on with out the ac. It got above 1/2 on the gauge and I finally had to turn the ac on for short periods. Done this before. Turn the ac on while going down a while or flat and level and turn it off on up hill sections. Got up in to some cooler weather and rain and made it to camp. Did a few trails. Engineer was no trougle from the Lake City side. Went over Cinammon from the Silverton side (steep side) and the temp climbed with no ac on and I get that strong smell and it runs rough. 5 days later we go up the Silverton side of Stoney (steep and long) in the cool mornin with fog and rain and it heats up again.

The temp gauge has a large normal area. The NOR is the lower half of the normal range and MAL the upper half. There are brackets that go above and below the letters. Everything seems to be fine if the temp gauge stays in the NOR or lower half. Problems start to occur at the A and L. When it hits the upper part of L I start to try to cool it down. Turn off the ac. Slow down to 55 or less. The temp will drop when I slow down going through a small town.

So ideas? Running lean maybe? Timing? Gas out west is 85 oct. and 87 around where I live. I'd just like to be able to drive it out west in the summer with the ac on and wheel it in the mountians. Sorry for the long post.

 

[Happy Jack]

A few more things I remembered. I replaced both O2 sensors, Purge valve, fuel filter, fuel pump, coil pack, plug wires, plugs ( may be time again). I've had the fuel system clean with BG products over a year ago and use a bottle of injector cleaner with every oil change. It was throughing a code when I first got it and I had the cam position sensor replace and it hasn't thrown a code since. The CEL will come on when I'm in low range on down hill sections useing engine compression braking but have not been able to pull a code.

 

[ThePhoenix]

maybe some cooler spark plugs?

 

[Turdle]

ok, first thing I would do is bypass the radiator trans cooler--
install a separate cooler for the trans. They could be "fighting" each other.

Also, check to be sure the lower hose is not collapsing when drawing coolant from radiator.

If there is no locking converter in the trans, it will make a lot of heat at speed. Keep this in mind.

 

[Happy Jack]

ok, first thing I would do is bypass the radiator trans cooler--
install a separate cooler for the trans. They could be "fighting" each other.

Also, check to be sure the lower hose is not collapsing when drawing coolant from radiator.

If there is no locking converter in the trans, it will make a lot of heat at speed. Keep this in mind.

I took the auto out over a year ago. It has the 5 speed stick (M5OD) that came in it from the factory again. I put the c-5 in Jr. with a different converter and used a cable to hook up the kick down instead of just stay strapping the kick down back part way. Seems to have fixed the overheating tranny problem in Jr. If I can get the overheating trouble in Green resolved well enough I have another c-5 and a Stubler to try out in Green.

This is all just engine heat that I am dealing with.

 

[Happy Jack]

maybe some cooler spark plugs?

I'll let um know. I don't do much with plugs. Just whatever is recomended in an Autolite or Motorcraft brand.

 

[MrShorty]

I'd probably look at the air flow through the radiator. Fins clean and reasonably straight? Is the fan clutch kicking in?

 

[Diff Whack Daddy]

The radiator could also be partially clogged. I had the same problem with a 92 a few years back. Took it to a radiator shop cause I was 3000 mile from home. They told me it had a bad head gasket based on some test to show that it had exhaust gases in the coolant. So I replaced the motor. Problem was still there after motor replaced.. Took it back to them and they finally agreed to rod out the radiator. Sure enough, the entire lower half of the tubes were clogged on the inside.

Solution, replace radiator with one from a junkyard and see if the problem changes.

 

[Happy Jack]

The radiator is only about a year old. It is the larger 2 core that was used in the auto tranny X's. I bought a new fan and shroud to match the thicker radiator. And I replaced the fan clutch and water pump and thermostat.

I have not done anything with the AC condenser though. It's in front of the radiator and would get all the dirt and bugs and stuff. The mechanic said he was going to run flow tests. I told him if he need to replace the condenser to do so or if the winch was blocking air to remove it.

Just don't understand why that big radiator is not cooling it. And why it not only does it at 70 mph but at 5 mph on the trail. But both times only when I work the engine hard going up hill. I did notice that the new shroud did not fit the radiator tight. Is there some type of seal or install kit that goes between the shroud and radiator?

Had a friend that had trouble and he just pulled the ac compressor and

 

[gmanpaint]

I like the torque converter idea, as well as the radiator idea. But how about a different angle of thinking. Not saying this is what it is, but just another approach idea.

How is the engine oil holding up? Does it get black and/or dirty fast?

The friction from broke down oil will allow friction to heat up the engine faster and a lot easier under a load.

If the infamous OHV pushrods are deformed on the tips, it slows the oil from circulating, creating sludge in the rockers and a slow drain.

Could remove the valve covers and have a visual inspection to verify. Cost a set of gaskets is all.

 

[Happy Jack]

It has no torque converter. The M5OD 5 speed stick is in it now with the 2 times larger radiator.

I changed the oil every three months or 3000 miles for the first two years. It was dirty when it came out and I keept that up. The oil pan is oily on the out side but it has never needed oil added between changes. I was expecting the Valvolene to clean it up but it did not seem to. Last oil change was at 5000 miles. I have always used Wix or Motorcraft filters.

The engine still has good power and dose not use oil between changes nor is it loosing coolant so I'm a bit reluctant to replace it and get the same results DWD did. But the engine oil does seem to get dirty fast.

 

[Anime]

The cooling system in these is VERY simple so there's not a lot that can go wrong.

Usually poor cooling is a thermostat that is stuck, or only partially opening. If the thermostat is known good (not the same as just being new, new ones can still be defective), then it's usually a bad water pump. As mentioned, it can sometimes be the radiator as well. There's also the possibility there's sludge buildup in the engine passages, or even the hose connections. A flush will help, but if it's bad enough, it will take several pressured flushes to clean it out enough to restore original performance. A new radiator in a system that still had gunk in the engine might have just had the gunk settle in the bottom of the radiator, so unless you know for sure the system is clean, it could still be an issue.

Something else to keep in mind with the 5 speed manuals is that using the auto trans cooling system isn't always a benefit. The heavy-duty fan clutch especially along with the 10-11 blade fans can put a huge load on the engine. The standard fan clutch and 9-blade fans the manuals usually have lets them run cool with a much lower load on the engine. There's a point where the load on the engine isn't moving any more air, but is just working it harder, which sucks more gas and makes it heat up past normal operating temp since it can't cool any better.

The thermostat and fan clutch seem to make the biggest difference, as far as I've seen. Be sure the thermostat is the correct temp range. A bad 'stat will let it go far past the 190-195 suggested range, even if it does finally open under pressure. Aftermarket fan clutches don't always work as well as factory. Sometimes they'll let the fan freewheel even when the engine desperately needs cooling, or lock up and do more engine loading than cooling.

 

[Happy Jack]

Ok, so have the BG coolant flush done again. I'll have to check on the fan. It is 1/2 in 1/2 out of the shroud now where I read it needs to be. Not sure if I changed to the standard fan it would be in the same place. Standard/fewer blade van might be too close to the thicker radiator.

On the engine oil, what is a solution? Engine cleaner (BG)? Oil cooler?

Thanks for all the help guys. Lots of great ideas.

 

[MrShorty]

Just don't understand why that big radiator is not cooling it. And why it not only does it at 70 mph but at 5 mph on the trail. But both times only when I work the engine hard going up hill.

This is the same problem I see with mine when the fan clutch goes bad. As Anime mentioned, some of the aftermarket fan clutches don't hold up very long. But you also don't notice they're bad until the middle of summer, climbing a hill at 5 mph (at faster speeds, the fan is less important).

Best test I've seen for a fan clutch involves removing the fan+clutch, rotating the spring 1/4 turn (CCW I think), then reinstall and see if the overheating is fixed. Rotating the spring causes the fan to be always engaged. If this fixes the overheating, then the fan clutch isn't engaging on its own.

 

[Anime]

Engine oil shouldn't be a problem. Just about any good name brand oil will do the job, as long as you are sticking with 5W-30. 10W30 might be okay in really hot conditions, anything thicker like 10W-40 or 20W-50 and you are overworking the engine.

DON'T use any oil additives.

If you want to "flush" the oil system, use full synthetic, a synthetic blend or just use one quart of synthetic in place of a quart of whatever oil you usually use. Motorcraft FL-1A filter.

 

[Happy Jack]

Great info. Is there a prefered brand of parts to buy? I've been getting discount parts house stuff for the last fan clutch, water pump, and t-stat. My oldest son manages a chain store and I just call him up for parts and pay him when he brings them over.

 

[Anime]

Motorcraft makes the best fan clutch, water pump, and thermostat.

 

[Maniak]

Great info. Is there a prefered brand of parts to buy? I've been getting discount parts house stuff for the last fan clutch, water pump, and t-stat. My oldest son manages a chain store and I just call him up for parts and pay him when he brings them over.

No opinion on the water pump, motorcraft stats are my preferred and Hayden server duty fan clutches are my favorite.

~Mark

 

[surf]

I like the Failsafe stats because they fail in the open position. Bosch makes a decent water pump.

 

[Happy Jack]

Well the shop said fan clutch so I had them out in another Hayden heavy duty. Took it for a test run today. Still started to climb this morning with the AC on. Got up to the A in normal. Went out to get an empty trailer we use to haul cars on. On the way home something let go. Sounded kind of like a manafold or something in the egr broke. Gas smell was stronger when we bounced the truck of bumpy roads/areas. When what ever it was broke all the way se lost power. But for a while with the ac on it would idle smooth. Got it home and turned the ac of. Open the hood and again extremely hot. Very strog order of caustic bad gas and a bad miss with a stumble every once in a while. Glad I did take it to Colorado day before yesterday.