Okay, so I got my Ultragauge over the weekend and was able to collect some info driving around today for a bit. I would like to get some feedback on what I am seeing...which, honestly, was shocking!

All in-town driving, 71 degrees and sunny, cool 15-20mph breeze.
Coolant temp rises quickly. It goes right past the normal temp range right on up to the low 220's, settles, then climbs again to 235-239, stabilizes. Then for no apparent reason to me (regular driving, no AC on), it will shoot to the high 240's to high 250's (259!!! was the highest). The dash gauge climbed up to the red zone, threw the red light at me for about 10 seconds, then went off, and it cooled back to 235 and stabilized there. At stop lights, 240-245, then go green it's back down to 230's, occasionally low 220's, but never dropped below 221.

Most of the time, other than the spike at 259, the dash gauge showed right in the middle, so slightly above, even at 244 it was only slightly above the middle range. That just goes to show me that the dash gauge is worthless.

So...what may be going on here? Clogged rad? I just don't get the temp spike, and then stabilizing in the 230's...which is WAY too hot anyway. And yes I do have tapping which sounds like a sleeve after it warms up.

I have the genuine grey 180 stat to put in this weekend. Work trip will take me away from home until Friday night, so I'd like to get some thoughts on this in the meantime.

TIA!

 

Bummer.... Was this a "new to you" rover?

 

Yes, new to me, but couldn't pass up the "deal". It's a super vehicle in incredible condition...except this cooling issue, which I knew about when I bought it.

 

Wow...I have a panic attack at 215. Those temps would make me pass out. There's a ton of info on here about diagnosing overheating issues. Especially now the outside temps are climbing.

Start with basics. Check colant level. Check to make sure coolant is moving. Check your fan clutch to make sure it's stiff when the truck is warmed up. Change the thermostat. Yes radiator may be gunked up on the bottom. Check to be sure your condenser fan comes on. Bleed the system per the RAVE manual.

My truck runs at 188.6 on the hwy w the AC on. And about 195-201 w the AC on. The outside temps here are 105-112*. I have a few minor modifications. But essentially a stock system. Get ready to hear you will absolutely need to do an inline thermostat mod to make the truck run cool. Not the case. If you are trying to cover an existing issue then yes. You'll need to get creative with cooling.

I run a HD Chevy fan clutch. A 180 thermostat. Now a large oil cooler (I've been told this won't help temps bu t it makes me feel better to have more oil and it being cooled off). All my hoses are new. I have a new radiator. I run a 70% water mix.

 

Good advise. Yeah Id freak if I seen 215 too!! I've seen 208-210 with heat soak on mine on a 110* day.....ONCE. Your condenser electric fan should come on at 212*, with the numbers you have, I'm sure its not. The condenser fan won't save you anyway...

 

Well it is parked until I get home and can dig in to it over the weekend. Thanks guys, I'll check out the list you gave me so far.

 

I'd almost bet money on there being air in the system. I'd definitely swap the thermostat, too. I won't tell you that an inline stat is the only way to get lower temps. That said, ill tell you its my favorite way and it gives you the most stable temps. If you stick with the factory bypass system, don't get anything other than the OEM 180. Not even the knock off 180, go OEM. You can do the inline for the same money, however, and cheaper for any future thermostats because it uses a Chevy style.

I've heard you can run some vinegar and water in the cooling system to clean out gunk, room not sure what the mix is, but might be something to try if your radiator is gunked. Some people argue that could break stuff loose that will clog cooling ports. My argument is that that stuff will eventually break loose anyway, in a less controlled situation, and possibly after it's picked up more mass to plug stuff easier.

 

IIRC the electric fan doesn't come on until the coolant temp hits 215˚ so I wouldn't have a panic attack at that level, but the other temps you share could be scary depending on how long they were maintained.

Since you already have the 180˚ stat on the way go ahead and install it and see what happens. (BTW is it an OEM 180 or aftermarket? Based on a lot of reports on this forum that distinction matters. EDIT - I see that in another thread you said you ordered the gray one. Good.)

Remember that assuming there are no leaks in the cooling system to drain it of coolant (and you haven't said anything about the coolant being low in your truck) there are only three other relevant components - the radiator, the thermostat and the water pump (setting aside the fan clutch which is irrelevant at cruising speeds).

The least expensive and easiest to change is the thermostat. You already have it on order do as I said above change it and see what happens. If the temp problem occurred suddenly I'd suspect the thermostat. That's what happened with my truck in January. It was running great with temps consistently in the mid-190s and BOOM, the temp spikes to 230˚. The thermostat was stuck shut, not allowing the radiator to do its job.

But because of the idiot light-like design of the temp gauge you have no way to know whether the high temps came on suddenly or were building over time and became apparent only once they got to a more severely high temp. (Again I didn't find the spec in a quick search of the RAVE but I recall the gauge starts to move at something like 235˚.) A more gradual increase in temps might point to a progressively worse problem with the radiator. Remember that the thermostat does nothing to cool the coolant; it only sets a lower boundary system temps (unless it sticks in the closed position). A system can run only as cool as the radiator's ability to function. A clogged radiator will cause the truck to run hot even if you were to eliminate the thermostat and run the truck without one at all.

And finally the water pump. It's extremely rare for the impeller to fall off the shaft of a water pump, and even more rare for that to happen with no other water pump symptoms. Given that, I'm going to assume it's either the thermostat or the radiator. Plus I'd guess the temps would be even higher if the pump wasn't moving any coolant and also would not fluctuate up and down.

A friend of mine had an '04 DII. Over time he changed the thermostat, the radiator and the water pump and the truck still ran consistently in the 210˚-215˚ range. Go figure.

 

I'm seeing lot's of D2's running around with stock thermostats which are completely stuck closed lately. My Java Black 02 D2 that I bought last year was a prime example.

Darn temps would skyrocket at idle with 229F being the highest I personally have ever taken a LR. I had no choice but to drive 211F all the way home after buying it. I immediately replaced the thermostat with a 180F unit and my temps went from 211-229F to 193-206F max range. The thermostat was original and it was completely stuck closed.

Also for as low as $90-100 you can get a new Radiator off of Ebay. If it's the original unit it's served the D2 well and IMHO it would be wiser to replace it vs try to clean it out. I love the performance of the OEM 180F grey thermostat enough that I'm not going to mess with the inline thermostat. If I did I'd like to try having my intake machined to accept the thermostat (like how most V8's are setup).

 

Totally missed the fact that you've already got the stock 180 to install. In that case, yea, totally go ahead and use it. I only promote the inline mod when someone still needs to buy whatever they use.