Heater fan motor replacement.

[66vairguy]

Another good article from South Coast Corsa's site about replacing the heater fan motor. There's more to it than just installing a new fan motor.

NOTE: I ran into an issue with the Clark's fan motor mounting screws. THE SCREWS WERE BLACK ANODIZED, which is an electrical insulator!!! The fan motor would not work as the screws did NOT ground the motor to the blower case!!! Not sure if Clark's ever replaced these WRONG screws. Screws are basic sheet metal type you can find at your local hardware store with shiny CONDUCTIVE plating.

LOG-IN to download .pdf file.

[34nineteen]

Is this removable with the engine/trans in place? My fan motor is disconnected, and I'm assuming it doesnt work.

I thought I read on the forum that the engine/transmission blocks removal of the fan motor assembly?

[steve57]

Is this removable with the engine/trans in place? My fan motor is disconnected, and I'm assuming it doesnt work.

I thought I read on the forum that the engine/transmission blocks removal of the fan motor assembly?

It can be removed without removing engine/trans. When I disassembled mine I took it apart in pieces, not a lot of room to maneuver the whole unit out. You only need to do this if you want to refurbish it, if just fan needs repair that’s not to hard to R&R.

[66vairguy]

The fan motor can be replace with the drivetrain in place, BUT it's not a fun job.

While your at it, if the fresh air hose from the engine top shroud to the heater box is torn (often is) then replace that. Not a fun job!!!! Many just remove the hose and put a block off plate on the engine shroud. A torn hose WILL result in #5 cylinder/head overheating. If you use a block off plate, then the heater fan has to be used as you loose the "COOL" pressurized air from the engine. Not a big deal, but I'm in a mild climate and on chilly morning to cars and coffee I set the heater slide to midway and just let the engine fan push the air through the heater without using the fan blower.

If you want to drop the heater box/assembly - that is nearly impossible with the drivetrain in the car.
I've only totally rebuilt two LM heater units and I did it when the entire drivetrain was OUT and even then it's a job.

Another issue --- CRITTERS sometimes get in the heater and plug it up with debris or WORSE, they eat the rubber flaps on the air doors in the heater box!!!!!

[34nineteen]

Helpful advice once again.

I've been going through my car and removing all of the garbage and debris that collects. I figured that could be the case with the heater blower motor, and a good cleaning once every 50 or so years couldnt hurt. I was suprised (but also not surprised) by the handfuls of debris I pulled out of the front fender area behind the fresh vent doors in the kick panels.

The initial plan was to backburner the heater motor until I was at a place I could more reasonably pull the motor/transmission, but if I can do it with them in place, I may just do that, as I am really wanting to get the accumulated dirt, grease and grime off the car.

[66vairguy]

Helpful advice once again.

I've been going through my car and removing all of the garbage and debris that collects. I figured that could be the case with the heater blower motor, and a good cleaning once every 50 or so years couldnt hurt. I was suprised (but also not surprised) by the handfuls of debris I pulled out of the front fender area behind the fresh vent doors in the kick panels.

The initial plan was to backburner the heater motor until I was at a place I could more reasonably pull the motor/transmission, but if I can do it with them in place, I may just do that, as I am really wanting to get the accumulated dirt, grease and grime off the car.

I recall it was the GM 1961 models that got the "flush through rockers" on the big cars. Rusted out rocker panels were a serious issue in the rust belt and GM came up with this design were rain would flush out the rocker boxes and air from the cowl would dry them out. Kind of worked, but leaves and dirt accumulate and stay WET. So you often see the lower front fender rusted through on 60's GM cars. I almost always find a pile of debris in the fender area behind the fresh air kick panel vents. Oh! NEVER PARK A CORVAIR UNDER A PINE TREE. The needles pass through the cowl vent slots with ease!

You reminded me that one of the Corvair "issues" is a STINKY HEATER due to oil and dirt from the engine heated air lining the heater system. Not unusual to find the long plastic duct (LM cars) in the tunnel full of greasy grime. I pull the duct and wash it out with Simple Green and a rag pulled through with wire (old coat hangers work). DO BE CAREFUL when removing the duct as it plastic and folks break them by being heavy handed. However, for 50 year old plastic, the ducts are usually in good condition. It's also why I drop and dismantle (and paint) the heater box to get the grime out of it. Yes the heater will smell like new paint for the first 20 or so mile with the heater on. After that it's fine.
Oh the duct doesn't mate well with the rear seat heater outlet box and there is sometimes a big gap. I use foam insulation for storm windows to fix the gap.

[bbodie52]

I discovered another indicator of "critter invasion" in my 1966 Monza sedan. When I turned the heater/defroster on and turned on the fan motor, I could hear a grinding chatter from the rear. At the same time, something of a cloud of debris that included bits and pieces of ground wood and leaves began to rain down on my padded dashboard as it blew from the defroster vents!






I guess the GM engineers in Detroit never imagined such issues when they designed the Corvair!

[bbodie52]

http://corvaircenter.com/phorum/read.php?1,420950


LM Heater Fresh air filter mod.
Posted by: davemotohead
Date: June 25, 2011 09:58PM

I always delete the fresh air hose coming off the top shroud and block it with a plate and gasket, and then install a 3" air cleaner on the fresh air intake on the heater to keep the dirt out and let some air in to mix with the hot. I have done this numerous times and it seems to work good, I like the wire caged air cleaners so you can dent them to clear the bell housing bump.

How does this affect (if at all) the heater hot air temperature? Does this lessen the "smell" many Corvair heaters have?

The LM heater box is like a mixing valve. There is a flap at the fresh air opening and one at the heater duct openings that connects to the lower heater hoses. The fresh air vent is normally attached to the fan shroud and it pumps air into the system straight off the fan. In the off or up position the heat flap is closed and the fresh air flap is open. As you move your heater control slide down its travel the fresh air vent closes as the heat vents open. So say at half way down, you have a 50/50 mix of cold and hot air = warm. If you move it all the way to the heat position or all the way down, the fresh air vent is closed and the heat vent is all the way open, giving you hot air right off the exhaust manifolds. If you block the fresh air vent off completely at the heater box all you will ever get is hot air. With this mod you will still get fresh air to mix with the hot, but it wont be pressurized from the fan. But it is filtered and still sucks in cold air to mix with, and no more worries about your fan shroud's hose cracking and losing air pressure going over the heads and overheating your engine. The smell is caused from two things: Having a leaking exhaust log packing is a bad thing and the other most times is burnt oil that has collected in the sheet metal or engine from a leak and it is burning off, So, no leaks and clean motor/sheet metal and no smell, I think guys were pouring simple green or something into the fan to get a evergreen scent in the heater?

[34nineteen]

Since I'm in Phoenix, and this is just a 2nd car for me to drive on nice days, I was actually considering pulling the heater. If its cold enough outside, I would probably just forgo the Corvair and use my truck anyhow. Part of me thinks I'd regret this at some point, and part of me really likes the Clarks headers.

I've already pulled the front heater ducts and cleaned them out thoroughly using orange degreaser and simple green with a soft bristled round brush. I was considering pulling the long duct out and cleaning it out as well, but it seemed like it would be a bear to get back in there without breaking everything.

I'm already pretty stinky as it is, so I dont need any competition from a vermin infestation.

Brad, I do like the Dave motohead idea, as just having airflow in the passenger compartment is a plus! Looks like he had some trouble getting that filter in there looking at the completed project. I probably dont need that much filtration, but a simple screen should do the trick to keep rocks and small animals out.

[66vairguy]

Since I'm in Phoenix, and this is just a 2nd car for me to drive on nice days, I was actually considering pulling the heater. If its cold enough outside, I would probably just forgo the Corvair and use my truck anyhow. Part of me thinks I'd regret this at some point, and part of me really likes the Clarks headers.

I've already pulled the front heater ducts and cleaned them out thoroughly using orange degreaser and simple green with a soft bristled round brush. I was considering pulling the long duct out and cleaning it out as well, but it seemed like it would be a bear to get back in there without breaking everything.

I'm already pretty stinky as it is, so I dont need any competition from a vermin infestation.

Brad, I do like the Dave motohead idea, as just having airflow in the passenger compartment is a plus! Looks like he had some trouble getting that filter in there looking at the completed project. I probably dont need that much filtration, but a simple screen should do the trick to keep rocks and small animals out.

Even if you don't use the heater - DON'T REMOVE IT. Sooner or later you may sell your Corvair and its value is very negatively impacted when the "heater parts" are missing!!! The exception is racing Corvairs.

Headers are tempting, but on a Corvair they are a PITA. Just too low and tend to get scrapped and dented. Unless you build a big cam racing engine, the stock 140 exhaust logs and dual mufflers are adequate. One issue with the stock 140HP mufflers is a small tail pipe exiting the muffler. Clark's sells replacement mufflers with a bigger diameter muffler outlet pipe and elbow pipe. They have a deeper sound, but don't "drone" at highway speeds.

[34nineteen]

Great! Thanks for the advice on that. I'll leave the heater components in place.

My car (probably) has the stock 110 manifolds, so I may keep an eye out for the 140's assuming they're cross compatible with the 110 heads. I dont have aspirations for a high HP motor, but when rebuild time comes around, I'm considering a 3.1 with a mild cam, and maybe bump the compression down a little to make it more streetable and pump gas friendly.

I may have to look for the attaching points for the underbody vents and pull them this weekend for a thorough cleaning, even if I wind up taping up the inlet end to prevent debris from getting back in until I get the heater blower motor sorted.

What are people using to replace the rubber (cardboard?) seals attached to the metal flaps on vent doors? I didnt see anything in the Clarks catalog, and mine are too far gone to figure out what was used before.

[bbodie52]

My car (probably) has the stock 110 manifolds, so I may keep an eye out for the 140's assuming they're cross compatible with the 110 heads. I don't have aspirations for a high HP motor, but when rebuild time comes around, I'm considering a 3.1 with a mild cam, and maybe bump the compression down a little to make it more streetable and pump gas friendly.

The intake manifolds on Corvairs are an integrated portion of the cylinder head casting. There are 4-carburetor kits available at Clark's Corvair Parts to modify the intake manifolds to add two secondary carburetors, but there is much more to the 140hp engine, as described below. The camshaft in a 1965 110hp engine is the same as the 1965 140hp engine, so switching to 140hp heads, carburetors, linkage, and exhaust would essentially convert the base engine to a 140hp engine. With all of those costly hardware changes, though, I think I would consider converting to an electronic fuel injection system https://ssl.corvair.com/user-cgi/catalo ... w_page=63B with dual exhaust and electronic breakerless ignition on the 110hp engine as possibly more-beneficial to a street Corvair. Both approaches are costly.

https://www.corvair-efi.com/

4 x 1 CARB KITS (converts 2 carb engines to 4 carb!)
https://ssl.corvair.com/user-cgi/catalo ... ow_page=63



The 140hp heads are somewhat rare and expensive. They can bolt on to a 110hp engine, and would fit properly on a 1965-1969 110hp engine. (The cylinder barrel outside diameter where it mates with the head is different on the 1964 engine).

This will give you some idea of the differences between the 140 hp engine and the 110 hp engine.

140 hp vs. 110 hp...

• Same high-performance camshaft on both 140 hp and 110 hp engines. Low performance camshaft in the 95 hp engine.
• Same 164 Cubic Inch displacement with same bore and stroke on all 1964-1969 engines.
• Stronger, nitrided crankshaft on the 140 hp and 180 hp turbocharged engines. (Nitriding is a heat treating process that diffuses nitrogen into the surface of a metal to create a case-hardened surface).
• On the 140 hp engine, a 4x1 carburetor arrangement, with two primary and 2 secondary 1-barrel carburetors, connected with a progressive linkage to open the secondary carburetors as you approach full throttle. (Equivalent to a 4 barrel carburetor on the 140 hp engine, vs. a 2 barrel carburetor (2x1) on the 110 hp and 95 hp engine).
• Dual muffler, dual exhaust with larger exhaust ports and larger exhaust manifolds on the 140 hp engine. Single exhaust on the 110 hp and 95 hp engine.
• 9.0:1 Compression Ratio in both 140 hp and 110 hp engines. 8.0:1 CR on the 95 hp engine.

140 hp Heads...

It's all about better breathing at full throttle at the high RPM ranges. At lower RPM the big valves and dual exhaust don't make much difference, and the secondary carburetors are not open for business.


110 hp Heads...

[66vairguy]

Great! Thanks for the advice on that. I'll leave the heater components in place.

My car (probably) has the stock 110 manifolds, so I may keep an eye out for the 140's assuming they're cross compatible with the 110 heads. I dont have aspirations for a high HP motor, but when rebuild time comes around, I'm considering a 3.1 with a mild cam, and maybe bump the compression down a little to make it more streetable and pump gas friendly.

I may have to look for the attaching points for the underbody vents and pull them this weekend for a thorough cleaning, even if I wind up taping up the inlet end to prevent debris from getting back in until I get the heater blower motor sorted.

What are people using to replace the rubber (cardboard?) seals attached to the metal flaps on vent doors? I didnt see anything in the Clarks catalog, and mine are too far gone to figure out what was used before.

Please clarify which "metal flaps" you are talking about. Heater box flaps, thermostat flaps on lower engine tin, etc.

As Brad said --- 140HP heads have larger exhaust "logs", so they won't fit on the 110HP heads. Going to a larger 3.1 Ltr is tempting and you'll definitely get more torque on the bottom end - BUT --- you are talking serious money and the bigger engine won't develop additional HP unless you go with the 140HP heads with bigger valves and extra two carburetors (secondaries). Be warned the 110HP is a sweet trouble free engine (relatively). The 140HP engine is a "tinkers dream" that requires effort to keep the two extra carbs working and clean. You also will need the 140HP distributor. Roger Parent four carburetor linkage is recommended (and it's handsome).

That said both my cars have 140HP engines and they look great at shows and I like the extra pull above 3,000 RPM. My engine size is 0.030" over so its basically stock and I have more than adequate power. If you decide to go the 140HP big valve heads, then PM me and I'll fill you in on some of the things to make it work better that I've learned from folks more experienced than me. Just me, but I'd put the money into 140HP heads (bolt right on a 110HP block as the cam is the same) and the dual exhausts. If you really have money to burn, then do the 3.1 Ltr. hardware.

[34nineteen]

Sorry, I was referring to the exhaust manifolds (logs). I think my car just has the stock ones.

As I understand it, the 140hp motor really doesnt come alive until its gets higher up in the rev range. I figured a little more grunt down low from the added displacement, maybe a slightly hotter cam than stock and keeping the stock heads would be a nice streetable combination. Right now I'm just spitballing this, as this project is a bit further down the road... and the larger displacement may or may not happen depending on how good or bad the cylinder bores look.

The flap pieces I'm referring to, I noticed mostly in the passenger compartment ventilation portion. I saw one on the cable actuated flap that routes air between your feet and the windshield. I think I'm seen some more, but I cant remember where at the moment. The one in the passenger compartment has about a 1/4" gap all the way around the metal flap to the side of the case, so I cant imagine it doing much good diverting air without it.

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I think I found your post on the other forum concerning this, and with a helpful pic of the orientation and mounting of the cardboard shrouds on the Y-duct. I was wondering how I was going to make those staples work!

[66vairguy]

Sorry, I was referring to the exhaust manifolds (logs). I think my car just has the stock ones.

As I understand it, the 140hp motor really doesnt come alive until its gets higher up in the rev range. I figured a little more grunt down low from the added displacement, maybe a slightly hotter cam than stock and keeping the stock heads would be a nice streetable combination. Right now I'm just spitballing this, as this project is a bit further down the road... and the larger displacement may or may not happen depending on how good or bad the cylinder bores look.

The flap pieces I'm referring to, I noticed mostly in the passenger compartment ventilation portion. I saw one on the cable actuated flap that routes air between your feet and the windshield. I think I'm seen some more, but I cant remember where at the moment. The one in the passenger compartment has about a 1/4" gap all the way around the metal flap to the side of the case, so I cant imagine it doing much good diverting air without it.

Capture.JPG

I think I found your post on the other forum concerning this, and with a helpful pic of the orientation and mounting of the cardboard shrouds on the Y-duct. I was wondering how I was going to make those staples work!

First --- the 110HP and 140HP cam is the same and they are not "mild". Keep in mind "in the old days" you boosted HP by moving the torque peak further up the RPM range (HP = RPM x torque). As the old saying goes "you advertise HP, but you drive torque", meaning the low RPM grunt gives a good seat of the pants impression. A more "aggressive" cam requires more volumetric efficiency (bigger valves, bigger or more carbs). BTW - today the Isky 260 cam is about as mild as you'll find and it's actually slightly more aggressive than the old 110HP and 140HP cam. The other issue is if you go with a 270 or 280 cam you need special valve springs to deal with the extra lift (without binding) and to prevent valve bounce at higher RPM. So if you want to boost low end grunt by a larger displacement AND keep the 110HP heads you'll probably want a 95HP or the GM turbo cam (3872304). I've heard California Corvair is sell new cams with the 3872304 grind.
BTW --- when you change the bore you have to do a CC calculation to determine how to cut the heads for the proper "mechanical" compression ratio. The fellow who did my heads (he's been doing most of the Corvair heads in S. Calif for many years) recommended a half point compression drop for today's "premium fuel" and cut the heads accordingly. Keep in mind bigger bore cylinders require the heads to be machined, so you might as well go for new valve seats, valves, etc. As I said --- big bore cost$$$ to get all the machining done. Reminds me of the old story --- Fellow walks into garage and says "How fast can you make my car go" the mechanic says "How much money to you have".

Second -- the defroster duct cardboard ---- DON'T try to staple it!!! The plastic is now VERY brittle at the top. I use A small screw with washers (to spread the force) and a stop nut (nylon insert so it won't come loose). I tighten the hardware so the cardboard will pivot some so it moves to fit up against the vent. NOTE: Some careful fitting and marking BEFORE you attach the cardboard is suggested. MUCH easier if the radio and ash tray are removed.

Third - The defroster/floor diverter flap isn't suppose to be air tight by design. I didn't use anything on the flap. With the fan on HI you should get more than enough air to either the windshield or floor. I've never had an issue with a well maintained Corvair heater. Once the engine is hot it has been reported by folks in Winter states as MORE then adequate. Maybe not up to today's standards, but by 60's standards it was a good heater (except when the pushrod tubes leaked oil and then it smelled awful). Keep in mind when the heater slide is up (OFF) NO air should come from the engine. If it does the heater box flaps are either out of adjustment - or the box door rubber flaps have failed (or been eaten by critters).

Note the diverter goes on the vertical duct and the flap swings into the duct to divert air into the floor area and NOT to the windshield. There is usually a gap between the diverter unit and the vertical duct it screws too. I use foam between the diverter and duct so more air goes out the floor vents instead of out the sides, which still heats the interior, but when your feet are wet and cold it's nice to get all the air coming out the duct to the floor. Not a big deal in mild climates.

[66vairguy]

Well this post got off topic --- LOL. Should have started a HEATER post.

I found pics of how I attached cardboard to defroster duct.