My 87 XJ Wagoneer stays cold.
It nevers goes beyond the first graduation after 40°, so maybe 70 or 75° (167° is US words..)
This is what the gauge says. I of course changed the sensor and get exactly the same reading as before changing it.

So maybe the gauge is faulty ? and not the sensor ?
Who has a good procedure to check in a different way ?

I touched the big hose and is remains cold for a while THEN gets (a bit) hotter.
so I suspect the Thermostat kicks in, so the coolant reached 80°.
Am I right ?

I have bought a thermostat for the front of the engine.
Could that be a solution ?

Thanks for your ideas.

 

Bien sur - a new MOPAR thermostat is a good idea if the temperature is not reaching the specified value.

You can check that the gauge is measuring accurately using an infrared thermometer pointed at the thermostat housing or back of the block where the temperature sending unit is. (I am assuming they used the sending unit at the rear of the cylinder head in 87). If there's an extreme difference in temperatures between the gauge and measurement with the IR temperature gun (considering you've already replaced the sending unit), then you'll know it is the actual gauge in the dashboard. If the IR reading matches the gauge, definitely start with a new MOPAR thermostat.

A new thermostat is a good idea regardless as a regular maintenance item.

I'm specifically noting that it should be MOPAR since Cruiser54, the resident Jeep Guru, insists on it being MOPAR. Many aftermarket brands have been known to be faulty, even right out of the box.

 

I'll do to replace my Crown unit. Surprising that such a simple piece can be faulty or quality sensitive?
Still, I really feel that the engine stays overly cool. so it might NOT be the sensor / gauge

What are the reasons that can prevent my engine to warm up ?

 

I'm running a Stant currently in my 95, and I do notice that it occasionally does not like to come up to the factory specified 210F. I have a MOPAR that I haven't gotten around to installing yet.

Crown has a pretty good reputation, and considering it may be very expensive or even impossible to be picky about part brands in your area, you should be just fine.

Aside from the thermostat, the only other things that you might check would be 1) Coolant mixture. Too strong a mixture can cause low operating temp. and 2) Radiator fans - I believe the 87 has the same 1 mechanical 1 electric fan setup as every other year, so if either one is stuck on (due to a bad fan clutch or electrical issue) it can force the temperature down.

I think you're on the right track with the thermostat though. Many brands are designed so that if they fail, they stay in the "open" position since running cool is better than overheating.

 

Looking at your location, Mopar parts may be hard to get or quite expensive. Personally I've used Stant Superstats in all my various vehicles since 1963 and only once had a problem with them. The one just stuck open.

rockauto.com has them for $1.85 USD whereas Mopar is about $25 USD. OE is 195* F.

A thermostat's function it to restrict coolant flow until the engine reaches set temp, then open to allow the rest of the coolant to flow thru to maintain that temperature. If the temp drops below set temp, it closes partially to maintain temp. I'm not sure what your jeep is supposed to run at, but most fuel injected jeeps run at 195* F to maintain good mixture settings.

 

Delete.

 

Like everybody else I was going to suggest replacing the thermostat but also wanted to say...

....sweet cluster gauge. That is the kind I want to switch in but yours goes to 120mph. The one I know of at a hidden junkyard like yours only goes to 85mph.

Edit: Just noticed yours is KM but they did make them in the US that did go to 120MPH.

 

Only with the police package.

 

Yeah, that's why I know finding any that goes over 85mph is low. But I do know where one on a wagoneer is that goes to 85mph with the RPM. It is at a junk yard that nobody really goes to anymore, and the wagoneer is one of the hardest vehicles to get to.

I don't really like the other style of cluster that has RPM.

Not really a fan of this style.

 

I'll do the thermostat and keep you informed..

 

There are two coolant temp sensors on an 87. There should be one on the side of the block under the manifolds. The one in the back of the head near the firewall is the one that drives the gauge in the dash.

 

I did my homework.
The thermostat is probably the issues...
I’ll change it during next week and tell you the result.

 

and what about the fan ?

it hardly turns by hand when engine is cold.

Could it be a reason for not warming up ?