how do I make my engine run cooler

Hey guys,
I already put hood vents into my rig, but I want the engine to run a little cooler. Any suggestions on a different radiator, or any ideas to run cooler? I would also like to run a tranny cooler. I have a 98 XJ classic

You can rewire your electric fan to run off a switch, so you can turn it on as you please. Get the right hood vents, it can look good, and do its job.

This is a good thread for a tranny cooler idea, just don't take my advice that I gave. http://www.naxja.org/forum/showthread.php?t=84541&highlight=transmission+cooler

Water Wetter works as an additive, I've been using it for years.

See about smoothing out the bends in the heater hoses - they still circulate coolant. That's why I put in the copper lines.

Makes sure there's no "casting flash" in the thermostat housing, a little turbulence there can go a long way. Remove with a Dremel and a sanding drum.

When was the last time the system was flushed? If you don't know, flush it now and restart the counter. The system should be flushed every two years - do a "hard" flush now, and you can just do maintenance cleaning later. I did the two-part powder (flush and neutraliser) first, then I can just do vinegar every alternate year.

Make sure you don't have any pressure leaks anywhere - since losing pressure will increase operating temperature (due to coolant boiling off.)

Mushy hoses? Replace them.

Fan clutch more than four years old? Replace it as well - I've not known them to last more than five, and I've only gotten three to four on XJs.

5-90

replace the thermostat. I changed mine couple weeks back and noticed about a 5-10 degree drop in deperature. quick and cheap.

New radiator cap helps, too.

smokeeaterXJ said:

Hey guys,
I already put hood vents into my rig, but I want the engine to run a little cooler. Any suggestions on a different radiator, or any ideas to run cooler? I would also like to run a tranny cooler. I have a 98 XJ classic

Click to expand...

Here's a few ideas:

Modine 2-row radiator
New 16psi radiator cap
Flush complete cooling system
Flowkooler high-flow water pump
Robershaw 180* t'stat
Replace clutch fan with an electric unit (minimum 14" diameter)
Redline water wetter
New radiator hoses (lower hose must have a spring)

A ported t'stat housing looks good but does bugger all for cooling.
Hood vents don't reduce coolant temps. but they do reduce underhood temps. You can help the latter even further by removing the engine skidplate, removing the plastic engine undertray, and insulating the underside of the intake manifold. Here's my article on the last one:

http://www.angelfire.com/my/fan/manifold.html

Dr. Dyno said:

Here's a few ideas:

Modine 2-row radiator
New 16psi radiator cap
Flush complete cooling system
Flowkooler high-flow water pump
Robershaw 180* t'stat
Replace clutch fan with an electric unit (minimum 14" diameter)
Redline water wetter
New radiator hoses (lower hose must have a spring)

A ported t'stat housing looks good but does bugger all for cooling.
Hood vents don't reduce coolant temps. but they do reduce underhood temps. You can help the latter even further by removing the engine skidplate, removing the plastic engine undertray, and insulating the underside of the intake manifold. Here's my article on the last one:

http://www.angelfire.com/my/fan/manifold.html

Click to expand...

x2.

I installed:
- new modine 2 row
- Flowkooler high-flow water pump
- Turbo City high flow thermostat housing
- 180 deg high flow thermostat
- shimmed the hood at the hinges

It never gets above 215 running in 97-103 deg desert terrain.

WOOT WOOT Post #400!

And one more thing from my experience. I did all of the above mods and my '92 XJ still ran hot. It drove crazy thinking I spent all of my money updating my cooling system and it didn't work. Then I noticed my temp gauge was reading 235-245 degrees when the thermostat opened. Turned out my sending unit was bad. This was my second sending unit so I installed an aftermaket Autometer gauge and now everything reads as it should. Just a thought.

If it's got alot of miles on it or the cooling system hasn't been serviced regularly, the coolant passages in the block and head will become restricted. All the thermostats, fans, radiator caps, etc... are a band-aid for the real problem. I have owned and rebuilt several 4.0's ,stock and stroked, all ran much cooler and with no cooling system mods after having the block and head soaked in the vat at the machine shop. The last 4.0 I built was an 87' model that the owner had been round and round trying to get an overheating problem solved. I'm not saying these suggested mods won't help the problem, but if you really want it fixed, do a complete or a "cheap" rebuild.

BIGWOODY said:

If it's got alot of miles on it or the cooling system hasn't been serviced regularly, the coolant passages in the block and head will become restricted. All the thermostats, fans, radiator caps, etc... are a band-aid for the real problem. I have owned and rebuilt several 4.0's ,stock and stroked, all ran much cooler and with no cooling system mods after having the block and head soaked in the vat at the machine shop. The last 4.0 I built was an 87' model that the owner had been round and round trying to get an overheating problem solved. I'm not saying these suggested mods won't help the problem, but if you really want it fixed, do a complete or a "cheap" rebuild.

Click to expand...

That seems a little (lot) extreme for cooling problems. Dump some vinegar in it and run it for a week and plenty of scale, rust, crud and deposits will loosen up. I'd try CLR, vinegar and any number of things before I yanked the engine and tore it down for a cooling problem.

Dr. Dyno said:

A ported t'stat housing looks good but does bugger all for cooling.

Click to expand...

Why? I have been eyballing the FlowKooler or HESCO pumps and the ported housing. Are you saying you don't like the housing?

The flowkooler doesen't look like much, but I'm not sure if the HESCO pump is really worth it either. Maybe for the 5hp, lol.

How hot is too hot?
I had a guy who went round and round with his 'overheating' problem.
Finally I asked him how hot it was running.....he said 210*!
Damn brother...they ALL run at 210*!
220* is acceptable...if you change the oil often.
over 220 and things start not liking it too well....

210 - 215*F is "design" operating temperature - but that doesn't mean I have to like it.

I've managed to pull my 88 down to about 190-195 most days (closer to 195,) using the tips I'd mentioned here, plus a few more in the upcoming "Cooling System FAQ" that I'm writing. It's really not difficult to do - and I've been able to get 195* op-temp with or without a thermostat (it just takes longer to get there without one.)

5-90

BIGWOODY said:

If it's got alot of miles on it or the cooling system hasn't been serviced regularly, the coolant passages in the block and head will become restricted. All the thermostats, fans, radiator caps, etc... are a band-aid for the real problem. I have owned and rebuilt several 4.0's ,stock and stroked, all ran much cooler and with no cooling system mods after having the block and head soaked in the vat at the machine shop. The last 4.0 I built was an 87' model that the owner had been round and round trying to get an overheating problem solved. I'm not saying these suggested mods won't help the problem, but if you really want it fixed, do a complete or a "cheap" rebuild.

Click to expand...

He's right...When I pulled the motor out of my 89 w/ 170,000 miles the coolant passages were almost totally blocked by crud...looked like barnacles on the bottom of a ship.I would do a chemical flush before I yanked the motor,though.

jeepdeepfreak said:

He's right...When I pulled the motor out of my 89 w/ 170,000 miles the coolant passages were almost totally blocked by crud...looked like barnacles on the bottom of a ship.I would do a chemical flush before I yanked the motor,though.

Click to expand...

I'd try anything before I pulled the motor, just telling you the root of the problem.