Maximum Engine Temperature

[aloharovers]

What is the highest point you can go safely?

Every highway grade sees me pulling over at 220. Wait 5-10 minutes and its back down to 185. Drive another 2 miles. Pull over.

Pete

[mhagie]

Is the radiator in the Land Rover large enough to handle the 6.2?
Merle

[aloharovers]

Hey Merle.
The Rover radiator is overkill for the stock 2.25 engine, but I didnt think it would be up to the 6.2. So I put a larger Griggon Aluminum in. Its got a 19x19 core.
I think that its still too small. I have done everything short of getting a larger radiator. The largest I can fit is the 27x19 core, but that will be my next step.

Whats funny is that for the first 2 years of driving the engine never really heated up except for hard climbs. Back in Seattle that meant I would just drive slow up over the cascades. Driving around town or my 1 hour flat commute it hardly ever got above 180.
Lots of steep hills here in CO smile.gif
Pete

[arveetek]

How many rows of cooling tubes, or how thick is the radiator you're using? What temp. thermostat are you using?

The stock core on the 6.2L measures 34.5" by 20.5", so it's quite a bit larger than your current setup. Heck, the 6.2L radiator is huge compared to most any other light-truck radiator. It's a lot bigger than the 454 radiators, even. My 4-row core radiator is 2" thick.

I just had my radiator repaired and rodded out last week. I checked into having a 5-row core installed, but that was going to be a $440 upgrade. The shop said mine was about 1/2 plugged up. After servicing the radiator and replacing the old 195* thermostat with a 180* model, I'm really shocked at how much cooler it runs now. I don't have actual degree marks on my '81 temp guage, but before the service, the guage would sweep up close to the 3/4 mark until the t/stat opened, and then remain at around the 1/2 mark most of the time. A hard pull made it run pretty hot. Now the guage goes the 1/4 mark and stays there. Haven't pulled with it yet.

Casey

[mhagie]

Actually I'm not sure as to how mine will handle the heat since my radiator is smaller than the standard 6.2 Rad.
Mine is the Modine replacement for a 80 454 4 row which is only 3 rows but with bigger tubes than the stock radiator 1/2 vs 3/8 I believe, they claim its more efficent than stock but time will tell.
The older radiator supports aren't set up to handle the width of the 6.2 Rad as my batteries set parralell with Rad support rather than at a right angle like the 81 and up.
Don't want to do a custom Rad but will have to
if the need arises.
Thats one thing I won't mess with is overheating it'll take our diesels down quicker than most anything else.
Merle

[aloharovers]

The aluminum radiator is twin rows made up of 1.25 tubes. I have a good seal with the fan to radiator. I need a larger radiator. I have accepted it now. The larger one will give me almost 190 square inches of additional frontage. I never had to deal with hills on the highway back in the PNW so never really noticed the problem before.

In Seattle I was running a 195 t-stat.

One of the changes I made here was to put in the 180* along with the hi-flow H2O pump.

[Stray Cat]

I was having the same problem with my old 6.2L-TC engine. I made a cooling mod that made a big difference. I will try to describe it:
-I plugged the bypass on the waterpump that goes to the heater.
-I replaced the block-off plate on the back of the passenger-side head with a threaded plate (the one used on the drivers-side to insert the glow-plug controller on early 6.2s) and opened the one on the drivers side. I had already tossed the glow plug controller as I set it up with a momentary switch on the dash.
-I put 5/8-inch nipples in the threaded holes.
-I put 5/8-inch hose up to a 5/8-5/8-3/4 "Y".
-From the "Y" I fed it back to the heater feed to replace the by-pass I removed from the waterpump.
That made a big difference! I ran it like that for some time, with much lower temp. When I replaced the engine, I added a 180-degree in-line thermostat to the mod. Here are the changes I made:
-From the "Y", I fed the hose into a 180-degree, in-line thermostat (I found it on-line; it goes on an old BMW and costs about $30).
-I put the by-pass of the thermostat to the heater.
-I put the output of the thermostat to a "T" in the coolant return hose to the radiator.
-The thermostat housing has a feed, by-pass, and output. The by-pass feeds the water out, at a limited flow, to the heater circuit, then back to the radiator until the temp. reaches 180. When the temp reached 180, the thermo begins to open and block off the by-pass to the heater and flow fully to the radiator. It looks like it was designed to go on the engine and works great with the dual thermostats (from Penninsular) on the front of the engine. I have one 180-degree and one 195-degree in there). The temp gauge sits at just above the 1/4 mark 99-percent of the time. Under heavy load, it will go to just below the 1//2 mark (200-degrees) and no higher. After the grade, it cools within several minutes to it's home just above the 1/4 mark! I love it! In addition to keeping the engine cooler, it balances the temps between front and back of the engine.

[Flat57]

Cat,

I'd sure like to see some pictures of your setup. I'm going to be putting a 1957 truck cab on a 1985 suburban frame/engine, and am going to have to do a lot of work to cool it since the 57's don't have a lot of room for big radiators. Do you have pictures or drawings you can send me?

[aloharovers]

Originally posted by Stray Cat:

-I plugged the bypass on the waterpump that goes to the heater.
-I replaced the block-off plate on the back of the passenger-side head with a threaded plate (the one used on the drivers-side to insert the glow-plug controller on early 6.2s) and opened the one on the drivers side. I had already tossed the glow plug controller as I set it up with a momentary switch on the dash. Sounds like a good idea. I also got rid of the 1984 style controller. I currently have a temp sender in the back of each head. Figured it was good to know if they were both the same temp.

Are you saying that you had a hose between the two heads, with a Y fitting leading to the heater?

Since I have an aftermarket radiator, my heater lines attach to the port in the H2O pump and in the crossover between the heads.

I have been thinking about putting a second heater into the back of the rig. Old Rover's are not known for their insulation value. Was thinking about using the ports at the back of the head for the second heater. Would also work as a 3rd radiator.
There is also the port up front used for the sender for the cold idle switch. Definately some options there for coming up with some alternative flow.
I really dont understand the port that goes from the water pump to the crossover/thermostat housing. With the radiator return feeding right into the the waterpump, I would think that opening would send 'cool' water up to the t-stat causing it to close early.

Has anyone ever seen a coolant flow diagram for the 6.2? I do not remember seeing one here on the site at all, and can't locate in any of my manuals.

I did order a new radiator. Current one has a 19x19 core. The new one is 27x19. Its the largest I can fit. Its a 50% increase in wind area so it should make all the difference. If this doesn't work I will get a stock size GMC radiator and mount it at the back of the vehicle on the rollcage like desert racers do.
Luckily this is my play truck and I can get away with that smile.gif Either that or just tow the Rover to the trailhead with my GMC :D

[Stray Cat]

aloha,
I was afraid that I would not be able to put into words very well....from your response, I didn't. Re-read my post and I will put together a diagram to post for all.

[aloharovers]

A drawing would be cool.

It does sound like you place a hose between the two heads, using the waterports located at the back of the heads. Hose has a Y fitting leading to the heater core.

Pete

[jcomp]

Has anyone tried turning down the fuel to help with overheating?

FWIW, I've got a brand new radiator, dual thermostats and a high volume water pump, and I still see coolant temps of up to 220 on a long hill or towing a load. EGTs never go above 900.

Oh and Pete, welcome to high altitude (and the problems that come with it). :D

[aloharovers]

Originally posted by jcomp:
Has anyone tried turning down the fuel to help with overheating?

FWIW, I've got a brand new radiator, dual thermostats and a high volume water pump, and I still see coolant temps of up to 220 on a long hill or towing a load. EGTs never go above 900.

Oh and Pete, welcome to high altitude (and the problems that come with it). :D Thanks, loven it smile.gif
I had to turn down my IP almost 1/4 turn from where it was at sea leavel to put a stop to the almost constant black smoke. Doing much better. I can still make it smoke.
But I still have the same issues. And I keep my EGTs down too.

Pete

[Jgreemo]

It seems like you guys are on top of this, but I'll throw in my two cents. I put the high flow water pump on with a new aluminum Modine 4 row for my new 6.5 and found HIGHER water temps than with the old motor and plugged rad. I traced the problem down to the coolant moving through the radiator too quickly to be adequately cooled. By switching to a lower volume stat (180*), it fixed the problem nicely and now I never see temps over
200* even when pulling in the mountains.

Good luck.