Temp gauge in heater hose, will this work ?

[blazer2007]

I have a 89 jeep cherokee and this home made fitting was installed on the heater hose for a mech. gauge but the gauge line was broken when I bought it. I would like to use a elec. sending unit gauge, never had much luck with the small dia. mech. gauge sending units ,seem to last a year or so. If I put a adapter to run a elec. gauge in this home made fitting will I get a proper reading with the sending unit being too far from the main stream of the coolant? I also believe he has it on the wrong heater hose, would it still tell me the temp? I still want to keep the idiot line gauge and don,t want to play with the stock fitting

[mongocanfly]

I wouldn't think so..I would think it wouldnt work if the heat was "off"...if the heater shutoff valve stops flow thru the heater core the line is gonna be cold
I wouldnt put it there anyway and cant imagine why someone did..
It needs to be in the head or block...

[Dead Parrot]

If the heater system has a on/off valve for water flow, then no, that won't work.

If the water flows full time, then maybe. In this case, I would install a T where the hot water exits the manifold/head and put your sender in that. Don't use any extension so the sender is as close to the fresh flow as possible. If you go this route, use one of those infrared/laser temp readers to see how close your new gauge is to what the temp reader shows once everything is full hot.

[kglowacky]

Now thats creative. Pretty sure it will give a temp but it wont be correct. I will give the installer A+ for the college try

[Axle]

It won't be accurate, but it'll be good enough for general monitoring. Just map it out with an infrared gun shot on the thermostat housing to see what your correction factor needs to be.

[blazer2007]

Thanks ,winter coming and I just use the jeep for winter,but when It gets well below freezing I put a rad blanket on the front to get better heat in the cab. but would like to know the temp as I don,t like a idiot light. Yes flushed heater core , new thermostat all the normal stuff but not giving me good heat at the below freezing. It,s just a winter truck so no big deal. I,ll wear a warmer jacket, just wanted a gauge.

[1976gmc20]

Ha-ha! Jeeps are great: overheat in the summer and freeze you to death in the winter

Is the vacuum shutoff still in place? Has it been converted to open system?

You know there is a cherokee forum

[hatzie]

The heater hose will always read lower than engine temp. If the valve is still in the heater circuit it'll read a lot lower.

IIRC the 258 AMC in my 82 Eagle Wagon had the coolant temp sensor screwed into a cast boss in the block about a third to halfway from the oil pan to the head gasket. If it's in the same place on the 4.0L it'll be along the same casting rib as the boss for the block drain.
I'd look into replacing the NPT block drain plug with your gauge sender.

[blazer2007]

Originally Posted by 1976gmc20

Ha-ha! Jeeps are great: overheat in the summer and freeze you to death in the winter

Is the vacuum shutoff still in place? Has it been converted to open system?

You know there is a cherokee forum

Got me on that one, have to find out what and where the shutoff is. I did join one jeep forum but when posting a thread I would get 1 or 2 answers and then no follow ups and still no solution. Some answers helped or would take a couple days for a reply.

[blazer2007]

Yes valve is still in place and is still a closed system. I didn,t know what that was called.

[1976gmc20]

Originally Posted by blazer2007

Yes valve is still in place and is still a closed system. I didn,t know what that was called.

I was going to just remove the valve in mine (1988) but the plumbing adaptions would have been complicated enough that I might as well just wait and maybe convert to an open system sometime in the future. I was going to pull and plug the vacuum line and just wire the valve open but it's at the shop for other issues right now.

IIRC, there are actually two factory heat sensors: one for the gauge and one for the electric fan. I believe the latter is actually in the radiator itself (which is one of the complications of converting closed to open system).

Anyway, cherokee no space forum dot com is where I get my information.

[blazer2007]

I know is not a jeep forum ,so I better stop. Just wanted to know about temp. gauges and if it would work which universal to most applications. Will check that forum, just need heat below freezing. Thanks gmc 20

[Corts60]

You really want to be measuring temp as close to the outlet to the radiator as possible. That's why you most often see senders located in the intake next to the thermostat.