Everything you Never wanted to know About Replacing a Stepdown Radiator

rambos_ride

Parts (excluding normal, clamps, gasket materials..etc)

• Radiator #433511 Orielly Auto Parts
• 7lb Radiator Cap #7007 Orielly Auto Parts (NOTE: I'm using a Vintage 7lb Relief Cap Purchased on ebay, fits a buick by default.)
• Upper Formed Radiator Hose #7096 NAPA Auto Parts
• Lower Universal Radiator Hose Unknown - replacement I bought failed..reused until I can order or make a 3 piece kit.
  
• Thermostat: #3476 Orielly Auto Parts - Application 86 GM C30 62 Diesel (someone mentioned Stant #13076..couldn't find a xref)
  

Radiator: #43351

• Modifications Needed: Zero Modifications!!!!!!
• Additional Parts Needed: 2 - 2-1/2" x 18" 16gage sheet metal strips to act as a filler between Hudson Radiator L Brackets (or a pieces of a No Parking Sign )
  

Fitting Radiator:

• Fan Clearance: use duct tape and tape a 3" section of 3/4" heater hose to the front of the fan - this will give you about 1" in reality when fitting and is min. distance...I had room to go over 1.5" from the fan..but everything I've read 3/4 is min. The more the distance increased the less efficient the flow will be.
  
• Radiator to Hood Clearance or "How High do I mount this thing?" At the core support center mount I straddled the bolt with 2 pieces of 1.25x2.25 pieces of wood..1 more piece on top to straddle the gap and give me more height..then a 1/8" piece of diamond plate merely used as a "shelf" to sit the radiator on while fitting.
  
  
• Center..just center it within the core support first.
  
• Loosely bolt up L brackets.
  
• Slide Radiator Down on "Shelf" and position as needed for fan clearance/centering...then use some duct tape to hold in place across the core support top of radiator.
  
• Take the 2 sheet metal fillers, position, mark and drill holes to mount to the sheet metal filler to the L-brackets first.
  Bolt the sheet metal fillers to the L-Brackets, then position L-brackets within the core support slots so that the back of the L-bracket aligns with the back of the Radiator Mounting Flange and tighten the L-brackets down..and re-check your alignment.
  
• Now mark, drill and bolt the sheet metal filler to the Radiator Mounting Flange.
  
• Re-check your bolts all around..you should be done fitting the radiator.
  

Thermostat #3476

I actually have a pretty decent looking stock thermostat (stat), but thought I'd save this for someone doing a true restoration (contact me..maybe we can trade?)

The stock stat shows you how the modern stat is a few thousandths too large in diameter not allowing the stat to seat correctly in the recess.

Both the thermostat that was in-place and the new one I bought were each the same diameter.

My first inclination was to just shave the stat to fit. But, that negates a quick road side fix..so decided to use my dremel on low speed..and late enough at night the coffee wore off...to shave enough around the diameter of the recess to allow the modern stat to fit without mods.

Conclusion
So far so good 2 days driving around town..2 days without blowing hoses or overheating...and Although it took me a week - I could now do this with parts in hand in under 2 hours!

[Deleted User]

Rambo - Did you block off the bypass passage in the therm. housing? This is usually done (one way or another) when using a modern therm. Norm

rambos_ride

Norm - yes, I made a full gasket with rubberized cork material so the bypass is blocked.

I think I might be getting some air pockets still..and I'm just running straight water the last couple days..I took temp at the top inlet 190-200 and 130-140 out the bottom so the radiator seems to be doing its job

I'll put anti-freeze in it tomorrow and that should lower the operating temps some more.

nick s

yes, I made a full gasket with rubberized cork material so the bypass is blocked.

rubberized cork just soundes to be begging to be pushed though the hole under pressure punching a nice rectangle of material free to plug a passage. the free plug in the passage would give me alot more piece of mind

I'll put anti-freeze in it tomorrow and that should lower the operating temps some more.

i thought straight water cooled better but boiled quicker than glycol mix, just saying don't be suprised by a rise in the numbers.

rambos_ride

This is fairly stout gasket material...I've done the same with other thermostat housings.non-Hudson..higher cap pressure..

How else would you block the passage off? The only other thing I could think of would be floating brass in the hole..but thats a big hole to fill...

GrimGreaser

I cut a gasket out of reinforced silicone sheet, put a 1/8 hole where the bypass is to let a little flow past. A proper plug can also be set into the bypass in the water neck, again with a 1/8 hole to allow a little flow with the t-stat closed.

SuperDave

If you can find a Hash water outlet.. It doesn't have the bypass passage, but looks exactly like the stepdown outlet. I found one in my junk stash and put it on my 262. The OH gasket set from Dale has both gaskets.

nick s

Dan, from another post on the subject, here is a pic of the plug approach.