VCCA Home Forums TECHNICAL - GENERAL Trucks and Vans Will a Harrison 3… radiator fit AD, 3100?

Gottum a couple of radiator questions.
Ran across a Harrison 3121499 HD 3” radiator for sale, stamped R07A 48J. I’m assuming that it was mfg Oct. 1948.
The guy said he got out of a early AD 1/2 ton. One of my parts books, 1929-57 lists itas fitting 1947-55 1, 1 1/2 and 2 ton HD 1st series.
And the other book, 1929-50 lists it as 1947-50 ALL COMM, and UTL. (heavy duty). It looks like it’s to thick to fit in the standard 1/2 ton core support, anyone have any knowledge about this?

Also the truck, a 1950, 3100 that I thought it might be a candidate for now has a Harrison 3128515 R11A 52K radiator in it. It is a couple of inches shorter than the standard 1/2 ton radiator that is in my 1950, 3600. I cannot find any listing for the 3128515 R11A 52K radiator and again, I’m assuming it was mfg. Nov. 1952 but I can’t find any Chevrolet parts book that lists that number. Anyone have any knowledge about this one? My thoughts were that it might have been out of something other than a Chevrolet.

Denny Graham
Sandwich, IL

In 1952 the core height on the 1/2 and 3/4 ton models was reduced 1 31/32". On 1 and 1 1/2 tons reduced 1 7/8".the horizonral air "cells" were also farther apart. The cooling system capacity remained the same. On the 5000 and 6000 trucks the core heigth was reduced 1 19/32". and the thickness 1/2". The capacity reduced by 1 Qt. The reduction was also made in the heavy duty radiator RPO for 3600, 3700, and 4000 series trucks. A 4 pound pressure cap was used to compensate for the reduction in cooling.
The 1952 passenger cars with standard transmissions also had radiator core content "reductions"....this all was due to the Korean war.
1952 parts book lists 3 3118968 as the standard @" core for 1947-51 up to 1 1/2 ton and #3121499 for the optional 3" core.
For 1952 the standard 2' core was 3128513 and the 3' was 3128514.
In general its best to avoid 1951 and 1952 cores as there was "decontenting" going on.

The H.D. radiator for 1953 5000 and 6000 trucks was 1/2" thicker.

Just because the numbers on the top tank are the same it does not always mean the core is the same.

Also the numbers can be different on the tank and the core the same. Example-on the 1949-1954 cars there were at least four different top tank numbers used.....not counting the 1951 models tha t were produced with a steel top tank that only lasted a year.



I didn't go back and check the numbers in the older books, will do that later.....its back to NASCAR for now.

Were due you find this stuff Gene!. Apparently somewhere along the line the original radiator was replaced in this ’50, 3100 with a ’52 radiator, which is what I thought, and that explains the difference in height. The number still doesn’t jive with any Chevy PN, it might be a GMC number.
Well the info in the parts books can be a little misleading as to the 3121499, 3” radiator. I guess the best way to see if it’s gonna fit in the ’50, 3100 core support is to pull the shorty and try and drop the fat one in the hole. Sure don’t look like will clear the cross bracing or the lower pan according to the tape measure. And as a matter of fact, I just ran out to the garage and looked at my stock original 1950, 3604 radiator and at the bottom there’s only enough room to just barely get you little finger between the lower pan and the lower tank. There is no way that you could squeeze a 3” core in there with out cutting an inch off of the lower pan and also on the 3104 the cross bracing inside the core support limits the clearance even more.

So in looking thru the parts books a couple of hours after I started this reply, and I see that the heavy-duty option not only had a thicker core but a different core support PN also. Now it’s starting to make sense. I don’t see in the parts books how they dealt with the upper and lower baffles, which would need clearance also with a thicker core support. There is no reference to HD for the baffles.
This is baffling!!!!

Remember Bruce, we are talking about the light trucks here so that probably accounts for some of the differences that we see.
Although you say you have a 3800 and that should fall into the light truck catagory also.
Denny Graham
Sandwich, IL

Denny, Are you aware of the GMC site.....oldgmctrucks.com.....you may find some radiator info there.

I can find no record of the 3128515 rqadiator either.
The number on the top tank is not aways the part number. Its only the Harrison number of the tank. This radiator may have been a unit used in production and the parts replacement radiators had a different number. This would have been done to combine numbers to make stocking of parts easier. An example. From 1937-1940 the cars with a 3.73 axle ratio had a rad. with the cooling fins closer together than the 4.22 ratio cars. The top tanks had the same number and the replacment rad. was only of one type which I would assume would have been of the "better" 3.73 car production unit.
The same in 1950 The Power Glide car had more fins and yet only one replacement rad. was sold.
The 3121499 rad. started off in the late '40's with that number on the tank and in the book By 1954 the tank still had that number but the part number was 3130812. Probably had some mounting bracket changes and the later replacement version came with multiple holes so it would fit all years.

The 52K may have been from an early 1953

The truck data books and option sheets don't list the H.D. radiator option for 1/2 ton trucks as Bruce mentioned.

I'll take your word for it about the tank numbers, but in my 1929-50 parts book copy every one of them say "part number stamped on". In my 1946-72 book all of the ones that show a number stamped on match the PN but the AD trucks cores have been discontinued at this point. Now the 1929-57 book that's posted on TOCMP, it does have some mismatches and yes, the ...499 is one of them.
I suppose by now Gene is saying "Well, here's another nice mess you've gotten me into Graham!"

Gotta go,
Denny Graham
Sandwich, IL

I would never say that......If I didn't like what I was doing I would just stop doing it.