Checker Radiator Repair - Part 1

Finding the problem

I noticed a bit of that distinctive antifreeze boiling smell when I parked my 1982 Marathon in the garage after driving it last year. I would frequently check the radiator antifreeze level and I noticed it was going down very slowly as the summer wore on. I did all the usual things to make sure it wasn’t leaking somewhere (though I did not see any drips or puddles on the garage floor) like a visual inspection under the hood when the engine was hot and even tightened all the radiator and heater hose clamps. The problem persisted.

One day when I had the hood open outside in the sun I noticed some green straining streaks running down the radiator fins in a couple of places. I figured that the actual radiator must have had some small leaks in it and that was where the antifreeze was leaking from and that the leaks were probably so small that it was vaporizing when leaking due to the pressure in the radiator. Thus the reason for the streak marks on the radiator but no puddle on the floor and for the slight smell.

Well, my Checker was 32 years old at the time and, other than change the antifreeze every few years and once or twice changing the radiator and heater hoses, I have never had work done on the radiator itself. I did have the heater recored once when it was leaking onto the floor of the passenger seat side (written up in a Checkerboard Newsletter article a few years back). Not a bad lifespan.

As it was winter when I discovered this problem, I waited until the following April to start the repair. I will describe it the best I can in case any of you want to try it on your Checker (or, after reading it, you decide it best to take it to a professional to do it!).

Fixing Simple Leaks

As you all know, the radiator is at the front of the car underneath the hood. Its purpose is to cool the water/antifreeze mixture that keeps the engine temperature under control. As the working engine heats the antifreeze (or so should I say as the antifreeze absorbs the heat from the working engine), once it reaches a preset temperature (it is under pressure so the boiling point is raised) a valve (the “thermostat”) opens and allows the hot water in the engine block to flow into the radiator where it is cooled by the air passing through it as you drive and by the fan driven by the engine sucking the air through the radiator. The already cooled water in the radiator then pours into the engine block to cool it off. And this repeats itself over and over again.

As an aside, when you have your heat on in the car, the heat lever on the dashboard opens a valve on the firewall that diverts hot water from the engine block through a “heater hose” that goes into the firewall and into a mini-radiator in that box underneath the dashboard at the front passenger’s feet. The heater fan blows air through this mini-radiator, heating up the air inside the car at feet level if set on “heat” or to the front window if set at “defrost.”

This hot water then routes back to the engine block via another heater hose from the mini-radiator to the firewall. If you have an auxiliary floor heater there are additional hoses routing between the heater under the dash and the mini-radiator in the floor heater under the drivers seat.

If you have a leak of your cooling system the first thing to do is find where it is coming from. This can be as simple as tightening one of the two radiator hoses or three heater hose clamps. At other times it may be that one of the hoses is leaking. Either is an easy repair job. They will result in some or a lot of coolant spilling out but such repairs are a good excuse to flush and refill the radiator with antifreeze.

Fixing the Radiator

If you have to repair your radiator you have to remove it. That is what this article is all about. Here are the tools I used for this job:

Pliers (for opening the drain valve on the radiator)
Open end wrenches (for removing the transmission lines)
Large socket wrenches (for removing the yoke over the radiator and the thermostat housing)
Small socket wrenches (for the radiator and heater hose clamps)
Sharp knife (in case you have to cut the radiator or heater hoses off their fittings)
Bucket (for draining the coolant)
Car jack and supporting jacks (to raise front of car to work underneath it)

It helps to be able to jack up the front of your car a bit and rest it on some heavy-duty jacks, as you will have to get underneath the radiator at some point. Don’t rely on the jack to keep the car up when underneath it! You don’t want to die doing this job. The first step is to drain the coolant from the radiator. Make sure the engine is cold, remove the radiator cap from the center top of the radiator (open it a quarter turn then press down on it and open it the rest of the way), put a gallon bucket underneath the left side (facing the engine) of the radiator and open the radiator drain plug, which is a small wing-nut type of screw located at the bottom left of the radiator (when facing the engine).

Drain Plug at Bottom of Radiator

There is a photo of this drain plug above. This drain screw is loosened with a pair of pliers and turned open a turn or two. If you turn it too much it will fall off into your bucket that is filling up with coolant but it can be screwed back in. Remember to properly dispose of the used coolant as it is a hazardous material (no pouring out back or down a drain, please).

When the radiator is drained it is only about 1/3 of all the coolant used to cool the engine. The rest is in the engine block, radiator and heater hoses and heater core. Needless to say, there is going to be a lot of coolant on the ground before you are done no matter what you try to do to prevent it.

Next you start removing the two radiator hoses. One is at the right top of the radiator running to the top of the engine block. The second one is at the bottom left of the radiator running to the bottom left of the engine block. Clamps at both the radiator and engine block hold these on. The clamps should easily unscrew using either a screwdriver or a small socket wrench set (with a long extension for the lower hose). Beware that even when loosened, the clamps will probably be stuck to the hose and will not move off. You can loosen them all the way so the clamp end pops out of the screw mechanism and pull it off or you can work a screwdriver underneath the metal clamp and the hose and wiggle it loose. When loose the clamps should be slid to the center of the hoses or removed.

In theory you should be able to wiggle the radiator hoses off the fittings on the radiator and engine block. However, I can assure you that they are probably baked on to the fitting (which, by the way, has a wider end on it that the hose has to be worked over that provides a tighter seal when clamped on). Try to wiggle them off and if that doesn’t work take a sharp knife and slice the hose length-wise a bit to loosen it up or completely cut it off. This is the time to replace these hoses so don’t bother to try to save the old ones for reuse. As you can guess, the bottom radiator hose is harder to reach and it is easier to remove by lying on your back underneath the car (a reason to jack the car up if you can) but before you do so puncture the lower hose to drain it of coolant so it doesn’t pour all over you while you are lying underneath it.

Next I remove the three heater hoses. Technically you do not need to touch these for removing the radiator so we will say this is an optional step. I suggest doing it as part of this project as they should be replaced too and what better time to do it than now when the car cannot run and you have the coolant drained. You hate to avoid this step, fill your radiator with new fluid and then a year later have one of these old hoses spring a leak requiring replacing your coolant before it is time to do so.

Take careful notes of where the heater hoses go to, as it would be easy to mix them up later. Two are longer hoses, one running to the firewall (and the heater core underneath the dashboard) and the other to the bottom of the heater valve bolted to the left side of the dashboard just above the heater core fittings. The third is a short one that runs from the heater valve front to the second heater core fitting just below it.

Like with the radiator hoses, remove the clamps [at the other end] (which may be baked on) and remove the hoses (which may also be baked on and have to be cut off). The locations on the firewall require you to be able to be on the passenger side of the engine to easily reach them (when I did this my car was in the garage tight alongside that wall and I had to reach them from the front of the car). Like with the radiator hoses there will be a lot of coolant that comes from them when loosened. Below is a shot of the firewall showing the side opening to the heater valve (top) and the two openings to the heater radiator, one with a heater hose still on and the other without the heater hose attached.

Heater Valve & Two Pipes to the Heater Radiator

Next, remove the two transmission fluid coolant pipes. These are the hard ones and are pipes that are attached to the inside left and right side of the bottom of the radiator that send transmission fluid from the transmission through the radiator to cool it down. This is more like working with plumbing now as we are dealing with aluminum and brass hoses and fittings instead of rubber ones.

First look to see if the two aluminum lines coming into the bottom of the radiator have ever been spliced to rejoin them. As you will find out, if your radiator had been removed before, the person doing so may have had trouble undoing these two tubes from the radiator. If they did you may see either a brass connector fitting a few inches from the radiator on one or both of these tubes or maybe a rubber hose splicing two ends of the aluminum tube clamped to both ends of the split aluminum hoses. You may be lucky if this has been done, as it may prove helpful.

Assuming that your radiator has never been removed or, if it has been, the mechanic did not have to cut and splice the two transmission lines, the way to try to remove these two lines is to undo the connecting cover that screws over the pipe into the threaded hole of the fitting attached to the radiator. You use an open-end wrench to do this. Doing if from underneath the car is easier than from the top. Some transmission fluid will leak out when each side is undone but not much.

The left side fitting came off rather easily on my Checker. But I could not undo the right side one. This resulted in having to cut the pipe a few inches from the radiator with a small metal pipe cutter, the type that you tighten over the pipe and twist and twist while tightening the knob on it until it cleanly cuts through the pipe. I bought a real small pipe cutter and, though it took a large number of revolutions, it did cut the pipe cleanly. You want to leave some of the pipe sticking out from the radiator so you can reconnect it with a connector fitting but not too much as you will never be able to pull the radiator out as the hose stub will not clear the radiator fans. I looked at my son’s Checker and both of these radiator tubes were cut and spliced, so it is not an uncommon way of doing this step.

The last thing to do is to remove the overflow hose that runs to the coolant capture tank attached to the inside fender under the hood. This comes out of the radiator-filling hole and is a rubber hose probably with a clamp on it. When I removed mine the metal nipple it was attached to came off too and I made sure to tell my radiator guy to repair it. You can see it sticking out from the side of the radiator-filling hole at the bottom of the hole on the below photograph.

Overflow Opening Nipple

While you are at it you might as well replace the thermostat. This is hidden in a housing that the upper radiator hose connects to on the top of the engine block. You have to undue the two bolts to reach it and you may need to carefully pry the housing off with a screwdriver. The thermostat is just sitting on the hole to the engine block. There is a paper gasket here and if you can save it do so as you will want to take it to the auto parts store to match it up with a new gasket. Below is the removed housing.

Thermostat Housing

Now all the hoses running to the radiator are off and it is time to remove the radiator. First of all you have to remove the yoke or cowl from the top of the radiator. This is just a matter of undoing the eight (??) bolts holding it on with a socket wrench (two of them also hold the hood latch in place). Remove the bolts then remove the yoke by lifting it up.

On my Checker there were two of those plastic clips that are used to hold two or more wires or hoses together at the bottom right and left of the radiator to hold it tight at the bottom of the radiator-fitting slot. I cut those off with a clipper. Once all this is done you just pull the radiator straight up from its slot, being careful if there is a stub of the transmission hose wanting to get hung up on the fan.

Now what? Well, take the radiator to the repair shop. I took my radiator to a local shop, Ferndale Radiator in Ferndale, Michigan on Woodward Avenue. They are a family-owned company (Melvin, the grandson of the founder runs it now) and work on a ton of radiators and heaters. I do not think they do the mechanical work of removing a radiator and I always just brought the removed radiator or heater to them. Ferndale Radiator works on a lot of radiators from older cars like our Checkers, getting them in from all over the country. The shop seems unchanged from the 19th Century. Matter a fact, I wonder if it was once a blacksmith shop that changed with the times as the automobiles replaced the horse as it has a large black fireplace in the shop next to the large tubs where the radiators are cleaned and inspected. Below is a shot of Mel with my radiator.

Mel of Ferndale Radiator

As Mel explained to me, Checker Radiators are what he calls “Harrison” radiators. Harrison built all the General Motor Corporation radiators for years and Checker bought theirs from Harrison as they had a GM engine in them. While another company builds them now, everyone seems to still refer to them as Harrisons.

What Ferndale Radiator does is clean the radiator in a large tub with chemicals then does a pressure test in another large tub to look for leaks, etc.

Mel gave me a call after doing this with mine and asked me to come down to the shop. I knew this was a bad sign. While there he hooked my radiator up with the air hoses and put my radiator into the pressure check tub. We both sat there looking at it. I saw nothing happening. Mel said that is what he wanted to show me, nothing! He explained that the core was about 80 or 90 plugged up! He didn’t know how my car didn’t overheat with it this way. Well, I guess that can be expected after 32 years of use. So, as expected, they had to order a new core for my radiator, which they did.

When the radiator was recored and repainted, I went to pick it up. As Mel was showing it to me he pointed out that I had three rows, from front to back, in my radiator. He said most have only two rows and so mine was better for cooling. I sort of recall that if you had factory-installed air conditioning in your Checker you got this three-row radiator core instead of the standard two-row one. Mel also pointed out something that I had forgotten, that the Checker radiators have a sight-glass on them on the inside top right corner. He said he replaced mine. This way you can see if the level of coolant in the radiator is high enough without removing the radiator cap to look inside or relying on the coolant collection container under the hood.

Mel also replaced the nipple at the filler hole that fell off and he also removed the transmission tube stub I had left and replaced the two fittings that the transmission lines attach to at the bottom of the radiator for me. These are odd fittings with a 45-degree angle for the lines to attach to so they are horizontal as the holes in the radiator point downward for some reason. The recoring cost me $400. Below is my radiator being pressure tested in the tub.

Radiator Pressure Test

Mel suggested that I use an AC Delco 15 pound radiator cap (that was what was on my car already but I replaced it as part of this job). He also suggested I use Ford Motorcraft antifreeze (the type for the older cars) as he said that was easier on the core (meaning didn’t corrode it as much as Prestone and other antifreezes tend to).

Here is a list of parts we need to replace the radiator. Note, I have a replacement engine in my Checker, a 350 V8, and these part numbers are based on this engine being in the car. If you have a V6 or straight six engine, the radiator hoses will probably be different as well as maybe the thermostat and radiator cap. I show parts numbers for these parts I purchased for my car or the Auto Value Store part number from the invoice.

Radiator Cap: AC Delco #RC26 (15 pounds)
Thermostat: Gates 74125909 (195 degrees)
Thermo Housing Gasket for thermostat housing: Gates 33624
Silicone sealant for thermostat gasket
Upper Radiator Hose: Gates 25478 (4.5 X 17 inch flexible)
Lower Radiator Hose: Gates 26509 (2 X 14.5 inch flexible)
Four radiator hose clamps (note top hose is larger diameter than lower hose so different sized clamps are required)
Heater Hose 5/8 inch, 13 feet (you cut it into three pieces)
Six heater hose clamps
Transmission tube splicing fittings;
Two 45 degree Male Elbow: EBD125520 (for 5/16th tubing)
Two 5/16 Union Connectors: EBD 162500
Two 8” 5/16 Poly Arm (to run from radiator to cut tubing if necessary)
Pipe dope
Antifreeze (concentrated, not diluted): 3 gallons
Distilled Water: 2.5 gallons