I posted this at van talk but figure this might interest some of you van owners with a slant six.

1 year ago I aquired a 1965 Custom Sportsman Van. Its a gold and white window van with all the trim intact, totally straight, black california plates with a 318 v8 motor. It ran OK but tended to overheat rather quickly when the summer rolled around. So i went through the usual methods to try to solve this:

1. had radiator rodded out and gone over.
2. changed thermostat
3. changed water pump
4 installed 5200 cfm electric fan
5. replaced all hoses
6. checked timing and carb

The overheating got WORSE and after discovering more and more rust coming in to the radiator it became obvious that the 318 was not circulating water through the water jackets very well. The previous owner had replaced the original 273 V8 with a motor which had sat for a number of years hence all the rust. I pulled it out and made plans to install a freshly rebuilt slant six.

"Wait" you say "why are you doing that?" Well the answer is kind of complex but a friend of mine has a Barracuda and REALLY wanted the V8 that was in my van regardless of it's issues and offered me his six cylinder. I have always been a fan of the mighty slant six and am much more familiar with that motor. I figured i'd rebuild it and do the swap in a few days - i'd get better gas mileage (i care little for performance with a daily driver and drum brakes to boot) and my buddy can do his thing with the 318.

OK well as some of you may know the six was standard in A100's but it is unusual in other mopars that they bolt up to a 727 tranny. Another friend had recenly blown up the six in his A100 pickup and offered me all the parts for conversion in return for my v8 mounts and linkage and what not. sounds great, everything will work. Only one problem- when i grabbed the large adapter plate which connects a slant six to a 727 bellhousing there is also a spacer included to mount the flex plate to the torque converter. We overlooked this spacer and left it attached to the crank of the old blown motor. In the time I grabbed the parts from my buddy and realized i needed this spacer he had scrapped the engine - spacer and all.

Boy oh boy. The search began. I live in southern California and feel blessed that there are so many cars in the salvage yards but alas the A100s are not quite so common anymore. I searched for a few months, checking ebay calling around and my responses ranged from "never heard of it" to "why the h%ll are you swapping a v8 for a slant six?"

Eventually the path led to a guy in oregon who had the factory specs for said adaptor and was able to manufacture one for me from scratch. Alright problem solved.

So the 318 comes out, slant six goes in. By the way my friend popped the heads off the 318 and scraped and poked an UNBELIEVABLE amount of rusty mud out of the water passages. It could have filled a shoe box. Even the oil pickup was 90% clogged with debris. Amazing how these motors can keep going. Now he's got it in his 67 barracuda with a four barrel and it runs fast and cool as a cucumber.

Back to the van - freshly rebuilt motor, rebuilt carb, new alternator, fuel pump, distributor, oil pump, plugs, wires, coil, cap, rotor, cleaned the radiator AGAIN, good to go. Everything works fine but ALAS when this sits in bumper to bumper traffic it OVERHEATS! No its not the temp guage. When traffic is moving and air is flowing it runs great at about 180 degrees but man when i slow down and sit at light after light in rush hour it pegs at hot. I am running the stock mechanical fan since my electric wont fit with the longer slant six in the small space between the water pump pully and the 4 row radiator i have in there. I even hooked up the electric fan on the front of the radiator to use as a blower when idling in traffic and it made no improvement.

So my question is this - Does anyone have advice on how this can be resolved? It is seriously blowing my mind. Are these truck so badly designed that modern overpopulation and traffic issues are too much for them? On the freeway it is great. Maybe in 1965 taking the kids to the lake didn't require sitting still in drive for 45 minutes. I dunno. It is telling that by 1970 Chrysler had pushed the motor to the front with the radiator right there so soak up all that sweet fresh air coming at it.

Maybe the 4 row radiator is too much for the little slant six fan? I dunno any 2 cents on this is greatly appreciated. I want my life back

Dave

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is your bellypan intact? missing one can cause overheat conditions since you won't be drawing cool air from the nose of the van, just hot air from under the vehicle and engine compartment.

-james

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Ditto on the bellypan.

Also, did you have your heater core cleaned out? If the 318 was a clogged as you say, chances are your heater core is also clogged. THis can cause your engine to overheat.

You may want to try asking this question on www.vannin.com THere are lots of hard-core van fans on that site who would be happy to help out someone working on an "early."

Good luck!

you might also check in with the early A100 group (think on Yahoo)

Ooops almost forgot - do you have a fan shroud? They really help. I have an extra if you're interested.

I appreciate the responses.

I changed the heater core with a clean one i pulled out of a '68 van i found in the salvage yard.

I do have the bellypan although i don't have a fan shroud. Hey Dartman what's the story on yours?

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My screen name says it all! Yo will need the shroud to help with cooling. Do you have a 4 or 5 bladed fan? I'm using the viscous fan which seens to help.
I had a run really hot problem, but not overheating when I got mine. Theres a plug on the slant thats aft of the distrubutor, pull it out and see how much gradoo is behind it. If there's alot, take a screwdriver and dig at it until its clean.
I had to do some major flushing to get my system clean. I use a mild mixture of muratic acid and H2O for a day of driving and flushed the snot out of it. I had to do this 3 times before I got the system clean. The gauge still read on the warm side till I took it to a radiator shop, he had one of those digital meters that he put by the thermostat housing and it was reading weel within coolness. I tinkered with the gauge and finally got it to where it read as it should.
Hope these idas help. Good luck!

Alright another A100 with a slant 6! To answer your questions, I am just using the regular 4 blade chrysler fan. I do have a six and a seven blade laying around but the angle of the blades looked almost too steep to use due to the real lack of clearance between the water pump pulley and the radiator. The fan on there now is like 1/4" away. Do you know if this is a big difference in air flow vs loss in horsepower to put a heavier fan on there? By viscous fan do you mean de-clutching? What is the size of your radiator? The previous owner had put a 4 row in mine which added to the space issue (although that was when the motor was a 318).

I'm definitely on the prowl for a fan shroud. It seems it has to be from another A100 as many others i've found don't fit.

I'm pretty sure my water passages are ok since the motor was apart and cleaned out not long ago.

Interesting about your temp guage - are they adjustable?

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I know that on early A-bodies the cooling system is designed so that the fan must be less than one inch away from the radiator or it will not cool properly. 69A100 is indeed talking about a clutch fan. If I were you I would run the seven blade since those A-100s need as much help as they can get in the cooling department.

I would run the seven blade and wire the electric fan to be a "pusher" in front of the radiator.

You might be able to use this formula to decide where the problem lies; it simplifies the problem by assuming that there is more-or-less uniform heating inside the engine:

T2= temp coolant entering rad.
T1= temp coolant leaving rad.
Ta= mean temp of air in rad.

v= 1/ log ( (T2-Ta)/(T1-Ta) )
e

v is a dimensionless cooling parameter that includes lots of terms (coolant volume, specific heat, etc.); if v>2, then you gain slowly by increasing the coolant flow; if v<1, you gain quickly.

The formula uses log base e - it didn't display quite right (often called "ln" for the natural logarithm).

I'll swap out the fans and see if the 7 blade will fit on there. Does anyone have an a100 fan shroud they would part with? Dartman?

Still curious about the temp guage thing.

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I too have an A van. Mine is a 69 A108 slant 3 on the tree, but will probably convert to an automatic. Have got as far as installing new brakes, hard lines, and soft lines on mine.

Caveman - sending you a PM about the shroud.

Sorry reed- NO I'm not talking about a fan clutch!! I never even mentioned it and if I were to, I would've! So don't go putting words in my mouth when you have no idea what Im talking about! As for a viscous fan, look in any mopar performance catalog and you will see what a viscous fan is, and what it looks like!
As for the shroud, mine is metal and almost looks like it is a afterthought, but could be wrong. The 4 row shouldn't cause any problems except for what you mentioned about being closer to the fan.

I thought you were talking about a clutch fan, also. Can you state the difference between a "clutch" fan and a "viscous" fan? Most people you the terms interchangeably (such a word?). There are actually two types of clutch/vicous fan. Centrifical and thermal. The centrifical type has Slippage built in, based on rpm and load on the fan blades. The higher the rpm, and/or the loading on the blades, the more the unit slips. The thermal type has a thermostat, built into it (bi-metal spring on the front) that controls internal valving changing the amount of fluid in the chambers inside the unit. The warmer the air the less the unit slips.

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Charrlie_S
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