So I have a 88 that runs about 225 and jumps to 235 when I'm in the freeway or I hammer on it. It does not run hot or hotter with the ac on, at idle or around town.

What I've replaced: water pump, thermostat, and obviously coolant.

When I drained the coolant it looked great(not brown and nasty). The rad looks new and does not seam blocked by the outside. I don't have lights or a winch in front.

All the barrings on all the pullies look/spin great. The belt looks good, not dried and cracking. However it does squeal when I first fire it up. Especially with the ac on but it goes away and does not do it again.

I have been reading alot about the cooling system and think I have covered everything. I guess what I want to know is if the 225* temp is bad. If it is I'm going to go to an open system.

 

Oh ya I don't have a fan shroud but I wouldn't think that would make that bug of a difference.....would it?

 

Before proceeding on any other tangent, replace the bottle cap with a 703-1396 from Napa.

 

So I looked that part up and it's calling it a non vented cap. Is that really what I want?

 

Yes. It's a 22 lb pressure cap.

 

So how would I know if my stock one is bad?

 

Because all the stock replacement ones are cheap chinese poor fitting, poor quality pieces of crap. You wanna fix this thing?

 

1) Check your system for pressure leaks.
2) Check your cap for pressure leads.
3) You've replaced your coolant - I'm assuming you did a flush as well?
4) Did you purge the air from the system? I usually drill two 1/16" holes in the thermostat flange, 180* apart, and install with one at the top and one at the bottom - makes the system self-purging. The typical method for "after-the-fact" purging is to jack up the rear of the vehicle so the engine is tilted UP at the rear, remove the coolant temperature sensor, and slowly add coolant at the bottle until it starts to run out through the sensor port. Reinstall the sensor and move on (if you want to seal the sensor, use Copper-bearing RTV or metal-based never-seez - the sensor grounds to the head, and conventional RTV and PTFE will interfere with that.

Once you know you have all the air out, adding Water Wetter (one bottle) won't go amiss, I've been using it in everything for years. I've managed to get RENIX op temps down to 180-195* with care and some simple mods, detailed elsewhere.

 

If it has the 4.0, make sure you get the air out of the cooling system. The 4.0 had a closed cooling system unfortunately, and air gets trapped in there.

As far as not having a fan shroud, it doesn't matter imo. My 87 has no fan shroud, the fan is in horrible shape after eating through two radiators and being halfway beaten straight again, worn out fan clutch, and never gets over 200 degrees. Even on hot days wheeling, where the Jeep spends hours riding trails never getting faster than 5-10 mph, it still won't get over 200 degrees.

 

1) if you mean by running it to pressurize the system then yes. And no leaks.
2) got the new cap from napa. No change.
3) yes the coolant is new. No I didn't flush. The coolant that came out looked great with no nasty crap.
4) I did purge it and drilled the holes. In fact after I let it burp I had a few drinks and while I let it cool I topped it off.

I have no clue what is going on. Every vehicle I have ever had, had an open system and never any thing like this.

I'm about to put in an inline filler neck and overflow bottle. Bad idea?

 

Yep 4.0. Good to hear about the shroud. I almost got one today. Glad I didn't.

 

The open cooling system will not cure any problems unless the problem is with the closed system, like the bottle not holding pressure. I suspect there are other issues here.

Now, there is still a chance your radiator is not flowing well even though the coolant came out clean.

If the closed cooling system bothers you so much, get a radiator that has a filler neck and a place for the fan thermo switch and put it in.

 

That was kinda my next step was the rad. I have done alot if reading and shopping around and I can't find a rad with the bung for the switch for the open system. Would it work/ has it been done, to drill and tap the tstat housing for the switch? Seams like a better place for it anyway. I know I could take it to a rad shop and have one welded in, not sure if I want to go that rout.

 

i would personally put the shroud back on and check the fan clutch. its cheap and will give you an answer right away. Then i would verify temps with my temp gun. Then i would pull the rad hoses and look for blockages (my 90 had the bottom hose internal spring actually break apart and i found what appeared to be bars leak all gummed up in there). What kind of t-stat are you running? I hope it's a mopar...if all else failed, and i was 100% positive everything else in the system was good, i would try running a restrictor (sounds silly, i know) in the top hose, just for ****s and giggles. maybe the fluid is moving too fast through the rad. maybe you have a steam pocket at the temp gauge sender too...

Good luck.

 

New fan clutch. New 180* tstat. Not sure if its mopar. It's from autozone. I have already spent almost $50 in just coolant. I don't know what to do now.