Question for the F heads

[60CJ5]

I finally got my temp and fuel guages working. :) (new sending unit and new gauges) BUT, the temp is at the upper end on the gauge. I have a 185 thermostat and I don't know what the radiator cap is. The Jeep was running between 190 - 200 on the aftermarket gauge I was using. I'm thinking about going to a 160 thermostat to see if that moves the gauge back to the middle.

I see that "early" F-heads should be 160 and late should be 190 and I'm assuming that 1960 would be early.

What thermostat and radiator cap are you running?

[vanguard]

I run a 190 degree.

[Glenn]

160 and a 7# cap in my CJ5.

[60CJ5]

Thanks.

[John O]

195 and 7lb cap. Air could be in the system. Remember the topic a while ago about air in my system causing incorrect reading and overheating?

[60CJ5]

I think mine is an issue with the wires. Both the fuel and temp gauges are reading F & H (pegged) I have new sending units, new gauges, new wires. I'm pretty sure the wires are hooked up correctly but I'm going to triple check that tomorrow.

[65CJ5]

I think mine is an issue with the wires. Both the fuel and temp gauges are reading F & H (pegged) I have new sending units, new gauges, new wires. I'm pretty sure the wires are hooked up correctly but I'm going to triple check that tomorrow.

Scott,

Check that your fuel gauge is grounded ASAP! If those gauges are pegging you can burn them out in short order (ask me how I know). The fuel gauge grounds through the rear of its case only if it's making GOOD contact to the metal of the speedo housing. Be sure both the areas of the fuel gauge case and speedo case that touch are clean. I even put a slight "dimple" in my speedo case to be absolutely sure it grounded.

Go to my site at http://frontpage98.nmia.com/~kittycat/ for detailed info on gauges (go to the Jeep section then the "repair" section and then click on "gauges") but it sure sounds like a bad ground on the fuel gauge! If it is you need to fix it pronto!

Stan

[60CJ5]

I guess I will be pulling the speedo out again!!! :evil:

Stan, my fuel gauge had a insulator behind it. Should I take that out?

[jat]

My 63 has a 160 degree thermostat and a 7# rad. cap. My temp gague reads abou 185 max when the Jeep is really hot.

[PeteL]

Scott,

Years ago I thought I'd get more out of my heater with a high-temp thermostat in an old F-head. What actually happened was it would boil over in extreme cold weather! ( = below zero).

I believe it was due to the thermostat being relatively exposed to the cold, up there at the front, and it never opened even after the block was boiling. Going back to a 160' cured it.

Good luck,
Pete

[davet]

7 lb cap, 195 degree thermostat, electric fan, engine stays at 190 no matter what I'm doing with it. When I ran the 180 thermostat it just took a little longer for the flat spot upon acceleration to go away while it was warming up.
I plumbed a 1 piece gauge right into the back of the manifold when I was trying to diagnose a cooling problem I had. I just kept that gauge screwed into the manifold and now can watch it with the hood up. By the way the cooling problem I had was the coolant cavitating at the thermostat and the coolant temp would go to 215 before the thermostat opened. I drilled a pin hole into the thermostat to let the air get by and that cured it. I think all thermostats have a hole or a notch in their edge for this reason but mine was being blocked by the gasket. :flag:

[65CJ5]

I guess I will be pulling the speedo out again!!! :evil:

Stan, my fuel gauge had a insulator behind it. Should I take that out?

YES. It's OK for the temp gauge to have that but not the fuel gauge. If you take that out and make sure there's good contact you should get normal gauge readings again.

Stan

[vajeeper]

I see that "early" F-heads should be 160 and late should be 190 and I'm assuming that 1960 would be early.



This info is new to me - what's the cut-off for 'early'?. I've got a 59 cj5 that overheated when idling in 30 degree weather. I recently replaced the thermostat with a 190 and was in the process of flushing the cooling system when it happened. Temp gauge is a brand new mechanical unit.

While draining the radiator I noticed the water coming from the bottom was way cold. So I'm thinking I need to:
a) possibly replace radiator (ensure water moves freely at least)
b) switch to 160 degree Tstat

I pulled the water pump and it doesn't have a bit of wobble. Any ideas guys?

[PeteL]

VAJeeper,

Are you sure the little bypass elbow (of 3/4' rubber hose) is functioning, to allow good engine circulation?

I would try the 160' thermostat - based on what I said on my earlier posting (above). It's possible the 190' is never getting up to temp, even though the block is boiling.

Also I'd make sure the thermostat's little bleed-hole is open, it might allow more hot water to reach the thermostat - but that's just a wild-ass guess.

Sometimes F-heads like to blow the head gasket between cylinders. The compression can then blow into the water jacket and "boil" the radiator over. You can use a smog tester to sniff for fumes at the radiator fill neck, and/or do a compression test.


Good Luck.

PeteL

[kiowamtp]

VAJeeper,

Are you sure the little bypass elbow (of 3/4' rubber hose) is functioning, to allow good engine circulation?



Mine wasn't even installed. I didn't know it was supposed to be there until another ECJ5er pointed it out to me. That would be a quick fix.

[vajeeper]

There was no bypass on mine as well. I found there's supposed to be one from looking at the cj3b page

I tried to remove the pipe plug in the head, and of course it stripped and even vice grips wouldnt get it off. I ground it off - I'll get it out w/an easy out I guess. I'm going to try keeping the thermostat i have and see how the operating temp improves with just the bypass.

Thanks for the help Pete and Kevin

[kiowamtp]

There was no bypass on mine as well. I found there's supposed to be one from looking at the cj3b page

I tried to remove the pipe plug in the head, and of course it stripped and even vice grips wouldnt get it off. I ground it off - I'll get it out w/an easy out I guess. I'm going to try keeping the thermostat i have and see how the operating temp improves with just the bypass.

Thanks for the help Pete and Kevin

I believe I ran one from the other side of the water pump to the back side of the head as well. I had two caps on my pump. If I remember right the other plug was for the heater.