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1990 K5 Radiator Updagrade

Here is the set up in this truck right now, it is a tinny little rad single core. But I also begin to wonder if the fan has anything to do with it as only 1/4" is sticking out past the shroud? I had always thought you need almost half the fan sticking out the shroud and half in the shroud. I wonder if someone has the wrong parts pieced together to begin with?

Fan 1.jpg

rad and schroud.jpg
 
ZooMad75 said:
Spectra CU774 for the radiator. I can't seem to find the part number for the saddles. I do know this, I'll had to do was tell my local napa I needed them for a 6.2L diesel squarebody and they got me the ones that fit.
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So I spent some time on Spectra website today and the CU774 is what thy have listed for the big block suburban as a 4 core rad. Long and short this is going to be my starting point.
 
CU730. Big block top plate from lmc and 4 new bushings. I run a shroud made by tejas steelworks that employs twin 97 camero electric fans. But i am running a 6.0L. I do believe this radiator was an option with hd cooling in the 90/91 burbs.
SPECTRA PREMIUM/COOLING DEPOT CU730 {Click Info Button for Alternate/OEM Part Numbers} Info
w/ Air Conditioning or Heavy Duty Cooling; w/ Transmission Oil Cooler; w/o Engine Oil Cooler; 28-3/8 in. x 20-1/4 in. x 2-1/4 in. Core; Replaces OEM 4 Row Core 90 v2500 burb 5.7L HD cooling and a/c.
Last picture was the first attempt at running a manual fan with the bbc shroud from lmc. Wasn't even close to being in the shroud with holley ls mounts. But it gives you some pics of the hd cooling set up.

IMG_20150820_123103041 (Large).jpg

IMG_20150821_053847587 (Large).jpg

IMG_20150810_223602953_HDR (Large).jpg
 
I put a 4 row in mine a couple of years ago. I used the big block upper plate style retainer, and of course, the lower brackets. There was never a factory shroud made for 4 row radiator, small block 4x4. I cut mine to fit the radiator side, but I have never trimmed the fan side to get the fan to shroud "proper".
I have a 11 blade plastic fan for a '98 tahoe, bolted to the '90 fan clutch. It works well enough to go wheeling with the A/C on, in black K5.
My shroud was for the tall, narrow radiator. (The original)

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Problem that I am facing at the moment to use the CU774 is that I run a dual battery system, and I have plow cables going out the front driver side. It appears I need to relocate the charcoal canister and also my plow cables...not sure

This CU774 must be a diesel and not a big block as the big block top plate does not fit the CU774.
 
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So is the radiator that @azblazer posted the correct width? That seems like the measurements are correct. He has the same top plate as I do.
 
Justin Fleming said:
Problem that I am facing at the moment to use the CU774 is that I run a dual battery system, and I have plow cables going out the front driver side. It appears I need to relocate the charcoal canister and also my plow cables...not sure

This CU774 must be a diesel and not a big block as the big block top plate does not fit the CU774.
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The CU774 will only fit with the 6.2 top plate, brackets and fan shroud. I saw those brackets on the website you noted and ordered them thinking I finally found somebody that had the elusive brackets. Sadly they are 3/4" short to the correct 6.2 brackets. The one piece top plate that @azblazer has on his won't fit either. I thought it would and @Larry had already been down that path and told me it won't fit. Same reason, it's too short front to back.

As far as the dual batteries, I'm running a Stock driver's side aux battery mount and it fits with the CU774 just fine. I did have to move my Battery isolator solenoid, but I just flopped it over to the other side and made a new longer cable for it. I think Larry deleted his canister on his Suburban, but there may be room to slightly to the outboard side.
 
Pictured here is the Big Block top plate from LMC Part number 32-0988 and the Spectra CU774 as you can see the big block top plate does not work with the diesel radiator.

diesel rad with big block top plate.jpg
 
Can the stock (separate) mounts for the smaller radiators not be modified to work with that? IIRC the wide radiator, as shown, used two separate brackets just like the smaller radiators, one just sits at an angle, further out. The threaded holes for it are already in every core support that I've seen.

Sorry if I'm stating something that has already been said, just seems most focus has been on the solid plate.
 
Justin Fleming said:
Pictured here is the Big Block top plate from LMC Part number 32-0988 and the Spectra CU774 as you can see the big block top plate does not work with the diesel radiator.

View attachment 250477
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Got a line on the right stuff yet?

This one just shows the brackets.
http://www.hillbillywizard.com/cucv...brackets-for-large-gm-radiator-diesel-or-454/

This link has the brackets, top plate but not the shroud.
http://www.militarytrucks.com/cucvparts.html

Now the part where I get blunt. Stop screwing around. If you wanted to use the same radiator I did why waste all the effort getting the wrong stuff when you were told what to get? Sorry dude but it's frustrating. No offense, but still. You got the radiator, get the rest and you'll be fine.
 
Well I am now changing directions as I don't want to rework my plow connections and cable, etc. So I am ditching the diesel radiator for now. I am going to try and locate a big block radiator. Seems like I am only finding the cheap plastic tank ones which is really not what I want to go with. If anyone has any suggestion on radiator manufactures or a part number for a true 4 core made from brass/copper please advise.
 
Didn't someone post up recently that Oreilly's is still selling copper/brass radiators for some applications? I know I saw something on that, just can't remember which application. I know the SBC "tall" radiator (19x27 or whatever it is) they sell is plastic/AL, but the copper/brass I saw wasn't ridiculously priced, at least not compared to what I was quoted to get the "tall" SBC radiator recored locally.
 
So I am still in the process of doing the radiator upgrade and also carefully inspection items for little gremlins that have caused some overheating issues that are not consistent. What I found was the water pump had some sort of coating coming off and I wonder 2 things. One is this enough of an obstruction to cause cavatation/air bubbles and two it is possible this stuff plugged up the radiator some. I am really not sure what it is, besides it looks like some sort of coating.

water pump.jpg
 
I wonder if that is some sort of stop leak product or something? Doesn't look like it would do the radiator tubes any good IMO. Never heard of any factory coatings inside the pumps, and can't think of a significant purpose a coating there would serve.

That seems to be a very odd impeller. Maybe I haven't looked at enough of them.
 
So I got everything back together and for the life of me I can not get the thermostat to open. I must have one hell of a air pocket or possible bad thermostat out of the box. I have pulled the water pump bleed screw, I have filled and topped it off from here. I then pulled the temp sending unit right next to the thermostat housing, coolant is there, I did top it off just a tad for good measure.

Question I have is should I see any flow in the radiator when the stat is closed? I thought if I turned the heat to hot I would at least see it circulating from the heater core?

I started thinking that the parts store gave me the wrong the water pump? Based on the part number on the box, it is the correct one, with counter clockwise rotation, unless a water pump got mixed up in the wrong box, I am not counting anything out at this time.
 
Did it overheat? I wouldn't worry about anything unless the temp is obviously going over what it should.

I don't recall being able to see significant flow through the radiator with a cold engine. Heater won't change anything unless you have one of the shutoff valves on it, which was apparently on some of the trucks. Mine doesn't, coolant moves through all the time. I would imagine if the pump was flowing the wrong direction, you'd see that flow moreso than if it was the right pump with a closed thermostat.
 
You could throw the tstat in a hot pot of water to make sure it opens.
 
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