M1007 - CUCV Suburban Clone Build Thread

M813rc

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No worries, my friend, Colton represented your family well. He is a fine young man, and a very positive reflection on his upbringing.

Cheers
 

Barrman

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I think I am a patient person. I also try and do things logically spending only money when it needs to be spent. So, when I got the truck on the road last June and it was running above 210°. I decided to do the next step up cooling system modification. I installed the Heath Diesel 21" plastic cooling fan and heavy duty fan clutch. I had a new Delco HO pump on the engine, but a several hundred thousand mile 1998 used fan clutch. It made sense replacing a well used and not functioning correct part.


I wrote about it at the time in this thread. It was much better, but I still couldn't run 70 mph with a load in high temps while pumping any kind of boost out of the turbo. Further researched showed I hadn't researched enough in the beginning. The HO pump casting doesn't mean it is the high output pump. It is just a casting mark for the foundry that made the housing. I could replace my HO pump with a real high output pump. Or, take the next step and get a 1999-2000 high output pump with a bigger front bearing, screw on fan clutch and bigger impeller.


Getting the screw on fan clutch water pump means a Kodiak Severe Duty fan clutch will fit. This is the same fan clutch the Duramax trucks used too. Of course, these bigger and better parts aren't cheap. It isn't just a step up, it is a walk up the staircase. Both in price and performance.

I lived with things as they were while it was cool out and saved up the cash. Now that it is getting warm again, I got everything ready. Monday, I brought the truck into my class and pulled the fan clutch, water pump, balancer pulley, balancer and front main seal. I was pretty shocked to find the coolant with was new 50/50 mixed stuff last spring came out a nasty rust color. I hadn't pulled the radiator cap in a few months. I figured out last summer my overflow tank works like it is supposed to so I just have been giving it a glance. Only nice green stuff in it.

Not oily coolant, rusty/dirty coolant. The radiator was rodded out last spring. All new hoses and new heater core. The only thing that wasn't new or cleaned out chemically was the block. I think it must have rusted some inside sitting for years since it was pulled from whatever HMMWV the military had it in. I can see that effecting cooling a little, but nothing is clogged and there weren't any chunks or clumps coming out. I will just refill with distilled water and do the garden hose flush once I get it on the road again. Maybe do the HE laundry detergent clean trick and thinking real serious about a coolant filter too.


We got it all back together again yesterday afternoon right at dismissal time. I fired it up, was really pleased to feel a breeze at my hands when holding them in front of the grill guard. Lots of air was moving! Then I saw a river of oil running onto the ground under the truck.

I shut it down, got rid of my students and went home without even looking for where it was coming from. I started looking this morning. Water pump and balancer areas were still pristine. I fired it up and saw oil getting pumped out of the mechanical lift pump vent hole. Not fuel, oil. Yeah, I love changing diesel lift pumps.


I checked the engine oil and it was the same basic level as before so I think it was just putting out oil, not fuel into the oil. I have several used ones, but since it looks like pulling the Banks cross over pipe is going to be the only way to get to it. I am only going to put a new Delco unit in there. I have one coming that should be here next week. Which is our spring break so I might have it back together again in two weeks.

The past two weekends I have driven almost 300 miles each in the Cowdog pulling a M101A2. I noticed my oil drip pattern had changed to not just under the front main seal to pretty much the entire front axle and passenger side frame rail. Not a bunch, but it was more. That is why I finally broke down and got the parts swapped out. Now I am starting to wonder how much the front main seal was leaking and how much was fuel pump all along?


The fuel pump on the truck will be the 3rd from last thing I have on the truck that wasn't replaced new when I redid things. Only the power steering pump and steering box are left. They are both seeping and are planned to get upgraded as money allows.

The moral here is if it rubber, has seals or is over 20 years old. Replace it while you have easy access. Like on an engine stand in a climate controlled room. Otherwise you will end up hugging a dripping oil and fuel front axle having to do it. Did I mention I can't wait to change out the lift pump?
 

rsh4364

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To simply the mechanical lift pump install, I used a tubing cutter to take 3" out of the hard line and used 3/8 rubber fuel line, double clamped on each side. Sped up the installation process. I have since moved on to an electric lift pump which I prefer.
 
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Barrman

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I just got done removing the lift pump. Turbo cross over pipe, turbo oil drain, fan, fan shroud, both radiator hoses and the pyrometer probe had to be removed first.

The entire time I kept thinking to myself "this better be the problem because I hate working on these stupid things..." The last thing I took off before the pump was the turbo oil return line and my heart just sank when the clamps were not much more than finger tight. NOOOOOO! But, when I got the pump off and turned it upside down oil just flowed out. Lots and lots of oil flowed out. The gaskets between the pump and the plate and the plate and the engine all looked to be good as well. This for sure was the problem and the hose clamps were just tight enough I guess.

Getting it back on still has me concerned. I have always done the rear bolt of the pump to the plate from the top. I can't with this because the turbo and turbo manifold are in the way. I guess the brail method is what I will use.

My hard line isn't secured to the intake manifold bolts like a stock CUCV. I also had to remove the mount next to the water pump for the hard line to get the turbo oil return line off. So, I can do the hard line last without any worry about lining the threads up like normal.

For sure on the 3/8" flexible line and the double clamps before the pump goes in.
 

Drock

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Forgive me if you mentioned this (long thread), but what size tires are you running? And are you running an overdrive trans? My M1028, Banks turbo, Gear vendors OD, 31" tires. Depending on which temp gauge I'm running :shrugs:. Will run 210°-215° at 70-80 MPH.
 

Barrman

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That information can't be more than 2 or 3 hundred post ago. Slacker...

3.73 gears, 35 inch tires, 4L80E transmission.

1800 rpm is right around 68 mph and 2000 rpm is exactly 75 mph. Most of my local speed limits are 70 and 75 so I am right in the middle of the torque curve peak at those speeds. I thought that would work to my advantage. Several threads on the diesel web sites claim an engine should be at 2500 rpm or higher to cool correctly. I will find out in a few weeks I guess.

Now, for towing I plan to run in 3rd with the torque converter locked. That will have me around 2500 at 65 mph which is about all I ever want to go when pulling really heavy stuff, if that fast.
 

Barrman

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We have had an unusually cool spring here. We have hit 80° a few times, but not much more than that and then only for a day and then it cools off again. Personally, I love it. Trying to test out my cooling system, it is trying my patience. We were forecast to be close to 90° yesterday and I had to drive 130 miles. Perfect testing conditions.

I was wrong a few post up about my rpm/mph numbers. 2,000 rpm is exactly 70 mph according to several gps receivers. I had found over the past few months that 1900 rpm made the engine really happy EGT and coolant temp wise. 2,000 rpm added at least another 100° to the EGT and used to make the coolant get over 210° after even the slightest incline when running empty. With the outside temps above 85°.

So, I set the cruise at 70 mph/2,000 rpm and went driving yesterday. I had done 140 miles on an interstate Friday at the same speed but it was below 65° outside. I got all the way up to 198° on a long hill, but normal temp was 196°. Yesterday was a repeat of that in the morning. It was cool out and the engine stayed right at or just a few degrees above thermostat temperature.

Driving in traffic in town with the thermometer saying it was 88° out had me hit 200° after leaving a traffic light and getting up to speed, but it would soon go back down to 198° and stay there until I accelerated again. This of course is with the a/c blowing cold the entire time. I wasn't drag racing, just staying with traffic flow.

Leaving College Station going home is a hilly pretty much constant elevation gain of a few hundred feet over 13 miles. Not much, but every hill top required boost and every down hill didn't really let off the throttle to maintain speed. I was at 202° when I got to a flat 10 mile long gradual down hill running against the wind. It only settled down to 200°. Then there is a 5 mile several hundred feet gain section of road. I have never finished this section of road at speeds above 65 with the coolant less than 212° running cruise control when it is above 80° out. I was at 206° yesterday.

6 degrees is all the improvement I got after all that work and money. I was kind of bummed. But, as soon as I got off that incline. It went right back to 198-202° for the rolling hills then next 40 miles. That is a huge improvement. Used to be it would hover around 210° the rest of the way home if I kept it above 65 mph. I kept the cruise at 70 mph the entire way.

Which means the performance of the truck has been improved a lot actually. I am now right at normal operating temperature for the engine, can attack hills at will and drive at the same speed as traffic. I am very pleased and could leave it like it is and be happy.

I won't though. There is still more degrees of coolant temperature to be dropped. I have a suspicion my "rodded" radiator is not nearly as efficient as it could be. The cooling fan should not be needed at those higher speeds to keep the engine at the thermostat temperature. Yet, it is so that means I will have to do a radiator when money allows.

If I went back in time a year. I would have gone with the Heath severe duty water pump, fan and fan clutch from the start and then known it was time for a new radiator then. Oh well, live and learn.

No oil leaks either by the way. Just a drip from the power steering box which is also on my list.
 

Barrman

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Well summer is here with a vengeance now. I can finally compare apples to apples on my cooling system. Another recap.

Last summer 95° outside temperature I was not able to drive more than 45 mph after the first 10 miles of everything getting up to temperature without hitting 215° or higher unless I backed off the power and basically coasted up hills.

I now have a Heath sever duty water pump, fan clutch and fan with the proper Delco 195° thermostat. Cruise control at 70 mph and it might hit 207° after a several minute up hill run of at least 3 psi boost. Then go back down to 202° or so as soon as I get off the power. Much better, but what about with a trailer? All of this before has just been running by itself. I want to pull stuff in the heat too.

Sunday was my chance. Colton has figured out his M1009, RED, is not the best commuter vehicle when he has to do 40 mile round trips of mostly stop and go city driving for his summer job. He is getting low teens for mpg and it gets a bit warm inside with no a/c. There isn't a full size or mid size SUV that gets much above or even at 20 mpg for his kind of drive. Since he wants the room but better mpg. He has decided a TDI Jetta wagon is the thing for him. They don't exist in his price range. However, gasser Jetta wagons are available for about nothing. So are TDI pull out engine and transmissions. He found a great gasser body and interior that supposedly even ran but had a transmission issue for a few hundred dollars.

We hooked up the car hauler to the Cowdog and went looking in 98° full sun heat. I found out real fast that I couldn't run 70 and keep it below 210°. 60 mph with the empty trailer kept us below 207° on the hills. We never felt the hills because the turbo just shot us right up them. The truck pulls great! I did hit 215° on a very long uphill run that include a highway flyover climb. Using my foot instead of the very aggressive cruise control dropped a few degrees right away. Once again though, as soon as we topped the hill or I got out of the boost. Right back to 203°. Which is where Bill Heath says the thermostat is finally all the way open. So, the water pump, fan and fan clutch are doing the job. It is the radiator that can't handle the extra heat. Something else that Bill Heath and I figured was going to be part of the problem the last time we talked. I wanted a nice hot day to confirm it though. I got that.

Once we loaded up the 4,100 pound wagon. The truck pulled great but I was limited to 50 mph on the open road to keep it below 210°. I never felt the load though. Up hill runs were just a bit louder with the tach a few hundred rpm up. 3rd gear not locked compared to OD locked. I need to get the proper switch and set up my compushift TCM so I can run locked at about 60 mph when towing. Running not locked in 3rd had the transmission fluid temperature up to around 190°. I have never had it over 173° before Sunday. I let it go to locked in OD and it would cool right down too.

Basically what I have learned is the Heath extreme pump, clutch and fan do work much better than anything GM put on these engines stock. I also learned that just because a 30 year old GM radiator has been "rodded" by a radiator shop doesn't mean it will cool like a new one. I need to buy a new one. Aluminum/plastic or copper/brass stock replacement? There doesn't seem to be a clear winner of that debate. I as well learned that my set up works! GEP 6500 with a Banks turbo, 4L80E transmission, 3.73 gears and 35" tall tires will cruise all day at traffic pace getting close to 20 mpg and will pull at least for now around 6,000 pounds without feeling the load and by the fuel gauge. Not drop be down to the single digits mpg wise.
 

Barrman

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1 year later. 15° coolant drop and 30 mph increase.

Post 314 has me detailing my first on road coolant heat issues a year ago. Several post since then have dealt with the steps I took to fix it. I wanted to be able to change a single part, observe the difference and finally say. “This is the part!” We’ll, I never got to do that.

Different 4 bolt fan clutch and a Duramax fan helped. Delco thermostat did too. Heath severe duty water pump and fan clutch really helped a lot in all situations except towing as the post above described. I new a newer than 30 year old radiator was going to be needed.

I had already decided I wanted an aluminum core. Copper/brass is more efficient in theory. Yet in practice research has convinced me aluminum is better for a radiator in my situation. Then the question becomes plastic tanks or aluminum tanks on the radiator. Chevy and every other manufacturer went to aluminum core and plastic tanks by 1993. But was that for cost, efficiency or both? On the other hand. You don’t see race cars with plastic tanks. They all have high heat exchanger needs and have aluminum tanks on the aluminum cores.

The internet diesel truck sites are full of threads where people buy full aluminum tank radiators for our trucks that bolt right in. By the way. A 6.2 radiator is very unique. Oil cooler, transmission cooler, heater hose fitting and low coolant level sensor port. I could find no other application similar. People claim the GMT-900 truck ones will fit. They don’t have an oil cooler though. All the radiators written about aren’t available anymore. I found one place that still has an aluminum tank aluminum core radiator that is a drop in to our trucks.

Radiator express actually ally has the plastic tank, aluminum tank and the stock replacement copper and brass units. I got the all aluminum one. 3 days after the order it was on my porch. 30 minutes to swap it in and then I couldn’t do more than just start it up and check for leaks until today.

Perfect day to test. Real high humidity, 95° temps and I had to make part of the exact same drive I did a year ago and got so hot doing. Since the Heath water pump install normal cruise temps have been around 201-203°. Today was 199° or lower on flat ground and up to 203° on hills with boost needed. Which dropped me 15° coolant temp from a year ago while running 30 mph faster.

Now i I need to pull a trailer and see what happens.
 

ken

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I used header wrap on the crossover pipe to the turbo. On my 82 GMC with a 6.2 and a banks. The lower rad hose is right up aginst it. I believe it was preheating the coolant. Mine does have a heat shield there but the shield gets so hot that I didn't think it helped much. With the wrap you can touch the pipe with out burning yourself. I also wrapped the exhaust pipe from the turbo down past the transfer case. It's amazing how much heat can be radiated onto the engine. The temps dropped from 205 to 190. After replacing the fan clutch it dropped to 180. I'm running a Robert Shaw 370-180 thermostat. The temp inside the cab also dropped enough to notice. I've had it this way for a good 20 years with no problems.
 

Barrman

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Ken, I wrapped the cross over near the radiator hose to protect it and the fuel line. I didn’t think about engine transfer hear. Good idea.

Thanks, Tim
 

Barrman

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Chris, I forgot to reply to your 2 core concern. Sorry.

I was leery of that as well. The stock 4 core has about 3/8" surface area front to back per core. Which comes to around 1-1/2" heat exchange surface area per row. Which has to be doubled to account for the top and bottom, but I don't want to throw too many numbers out in this simple explanation. There are around 30 rows in the stock copper and brass radiator. The core channels are closer to round than flat.

I called and talked to someone at Radiator Express to confirm what their website says about core width. A bit more than 1 inch per core with more than 40 rows. The aluminum cores are more flat than round allowing more to be stacked vertically than the round copper/brass ones. With more than 1/2" extra surface area front to back and the increased rows. I felt it was worth trying. Add in no solder to hold it together and that the copper/brass unit was another $100 more expensive over the already expensive purchase. I went aluminum. That make sense?

Ken and has wrapped cross over pipe has had me thinking. I only have had coolant temp issues when I am making boost. Specifically above 2.5-3 pounds of boost. It will cruise all day long at 2 psi or less without issue. I have been going along with the idea it is cylinder head heat causing the coolant to go up. I have been trying to find a correlation between the EGT and the coolant temp but air changes temperature so fast and liquid so slow. I just haven't been able to connect the dots. Maybe I should figure out some way to mount a camera to watch the boost/egt gauges and another to watch coolant temp. Take video and then graph things out?

I will do some trailer pulling once it gets hot again. This week is supposed to be mild with lots of rain. I already know it works great below 90°. After I get a handle on what it averages out to. I might pull the cross over pipe and wrap the day lights out of it on general principles to see what changes. I already have the down pipe wrapped to mid transmission. Plus a turbo blanket too.

If none of this works to my satisfaction then I am left with intercooler or water/alcohol injection as the next step. Or just drive slower when it is hot out.... Nah.
 

ken

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Tim,
I was thinking since the turbo is heating up the motor oil when the EGT's go up. Maybe adding a extra oil cooler could remove the excess heat from the oil. A cooler along with the rad oil cooler might be enough. The hotter oil is most likely heating up the coolant since it is on the cool side of the rad. Maybe one from a 90's 6.5. Since the hoses are easily acquired.
 
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