What kind of auto parts stores do you have? It is a basic GM size thermostat, pretty common. See if they have one for a Chevy pickup, and compare sizes. When I checked ORielly Auto parts, the 180 stat that fits 88 Rover models also fits 3597 GM models... And you can run without the stat to see if you still have the same problem. The stat determines how cold the engine will get under normal conditions. If it sticks, sure it can go hot. Now as to the 160 rating:

My truck would run at the temperature of the stat in the mornings, but in the later afternoon, with temps in high 90's or above lately, it would creep up to 199 - 207. I had already put on the larger fan, so I decided to experiment with a 160 stat.

So the truck would run at 158 - 163 in early morning, no AC. Add AC and it moves up about 10 degrees.. Afternoons, still moved up higher. 16 mpg, so no big change.

I have decided to go back to a 180, because most of the readings I saw when running that were above 160 would still be under 180. So the thermostat would still be in control of the water. That is important, even on hot days, because the stat closing allows water in the radiator to have time to cool off. If system is hotter than stat, it is wide open all the time, and has minimal control.

Now really old skool had 160 for summer thermostat, and 180 - 190 for winter so heater would really put out. The pollution control rules changed all that, they want a constant high temperature to reduce the bad exhaust byproducts.

If you fix problem with a $10 thermostat I'll be surprised. But it is a cheap and quick thing to try.

As to high temp operation, people go out to Death VAlley and the desert areas in the 120 's. There is the Saudi grille modification, if you wanted to see if that would work for you, just take off the front plastic grille. There's a write up on it in the tech sticky.

 

We have all the majors here...Western/Advance, Autozone, PEP Boys, Sears....good to know on the thermostat and yeah I'm sure wishful thinking.

But let's rule it out. I'm kinda old school and it's always summer here and I don't drive it enough to worry too much about smogging up the air. I can offset somehow.

Dealer wants $40 bucks for it. Sells for about 10-15 dollars in the UK. Cannot find it here yet. Not sure how to tell which Chevy Thermostat to try...measure it??

Saudi Grill mod is definitely in my plans and my skill-sets.

You've been very helpful. I need to send you something.

Add. I found the 165 thermostat (ETC4761) part locally. They say it's for a Jag and it's $12. I think I'm going to go with that one. With the constant hot weather I can't see the need to swap that out anytime soon.

 

Auto Zone #15358 or 15356 should do it, can't imagine they would have different stock numbers.... If all else fails, go to store, have them show you one for a Land Rover, then compare to one for Chevy, etc. They use the same gasket and bolt holes for gasket.

 

One thought - since your previous mechanic did disable the heater, and such, it is possible that at some point someone may have put in a bottle of stopz leekz. In addition to clogging up radiators and reducing their cooling capacity, the actual leak stop material can coat tiny cracks. Like the one that is the seal of the thermostat, which can make it stick or alter its performance. Some stop leak products suggest removing thermostat during initial application. So thermostat could be a problem. But seems like that would show up with 20 minutes at idle.

 

SB -

Did you see the picture of the heater reroute? Does it look ok? Another mechanic told me I should reroute it but I'm not sure how he meant.

The heater bypass thing was a roadside fix with a long forgotten purpose. But I doubt anyone added any stop leak here. More likely, sawdust as someone else mentioned. But I don't think that is it.

After I replace the thermostat...if it continues to get hot, I believe I should do a pressure test. That would determine the flow issues you allude to...correct? How do people say they have a 75% or x% radiator performance. How do you know?

It's monsooning right now, fyi. Wish I had those headlight washers still in.

 

I some how missed the photo post and went back to look at it. Solder joints may not be artistic, but look like they will hold.

As to the re-route of hoses - normally the pipes capped off take water under the dash to a valve, and either into the heater core or back thru the other pipe directly. So even if the heater is not turned on, warm water is under the dash and back out. That's how we hear the rushing sound of bubbles going by. I would get the correct size piece of heavy duty hose and replace those two end caps with a "U" that does not crimp when bent. That way what ever flow goes that way has a means to return, and it may impact some internal pressure balance issue inside the pumping system that is screwing up the flow thru the radiator.

Pressure test tells you that you have a leak. Could be to outside, could be into oil pan (oil should not look milky), could be into cylinders or exaust. Usually go up to 15-18 PSI for 20 minutes or so. Coolant cap vents at 15 psi.

A flow test tells you how much water is going through something, like the radiator. DIY test is to disconnect upper and lower hose, put in a garden hose, and see if it can keep up. If not a decent flow, time for rod out. While you have hoses off, connect garden hose and rag to lower outlet, and reverse flush for 20 - 30 minutes. Should see some scale come out.

A radiator like these is a cross flow or horizontal tube radiator. The bottom tubes usually stop up first. That makes them cooler. Dont touch by hand for too long, but an IR thermomenter can point at it and see if temp is different. My rad indy shop says about 10 degrees spread for a radiator in good shape.

Have heard of sawdust in other things, like gear boxes. Have heard of ground up walnut (?) shells in cooling (may be part of that majic stopz leeksz formula).

 

One of my heater pipes blew out at the firewall one time while on a trip. I made it to an auto parts store and they let me back to look at coolant hoses. I found a moulded one that was a long 'J' shape of the right ID. I cut off the long leg and had a perfect 'U' to route the flow from the supply right back in to the return pipe.

Once I fixed the heater pipe I put the piece of hose in my spares kit for an emergency.

 

Tom,

That's a great idea, because most of the Rover heater hose array is metal pipes.

I was thinking that since the water normally flows in/out of those pipes it would mean that the areas of the block involved in carrying that water flow might not be getting the cooling Rover engineers planned on. With tubes blocked off, no flow. Not like old Chevy's when we could put a hose bib valve on the firewall and make our car cooler during the summer (too cheap for AC)

 

Replaced thermostat with 160 degree.

Replaced radiator cap with temporary fix which is working. Will order correct plug.

BUT THE PROBLEM WAS....my viscous was bad and then my metal fan mod went bad. I think they sold me the reverse fan which looked right in the pic but pushed the air in the wrong direction. I put the original fan back on. Too bad I put that $40 mod on the $26 fan but now that the truck APPEARS to be running great...i don't give a....

Please don't let this be one of those posts that I revive in a few days with a "still overheating.." title.

Oh, and bought the water temp gauge that Tom pointed me to, but the white one that glows 7 different colors at night.

I don't quite understand what you guys mean by that heater reroute but I'll start digging into that shortly.

I'm learning a lot of lessons. Many the hard way....but I think my HG's are in good shape.

Thanks for being there!

 

On your heater lines that are capped with hose clamps - they are close to the front of the engine and will be warm when running, because there is water inside them.... I suggest you remove the two caps, and replace them with one "U" of the same size hose, but not bent so tightly that it kinks in the middle. This way water can flow in/out, and that may improve your cooling.

So your new viscous clutch was bad? It looks so good. By the way, in the second pix you posted, there is an arrow on the label. Would that indicate direction of rotation? Yep, the curved side is toward the right way, but the opposite "attack edge" - I'm not sure if you would improve it by flipping the fan over. Knowing that you don't want to buy new blade, and machine shop work on it... consider blade from a used Chevy truck of late 1990's - early 2000's - will bolt right up, and I trimmed mine with kitchen shears, it is nylon. So how does current set up do at idle, and at high way speed up the mountain? Are you using stock fan with new clutch?