I thought I had this overheating thing licked, but apparently not. I'm OK around town and sitting in traffic, but if I drive around 40 mph or above (I RARELY go over 45 anyway) it slowly heats up. It doesn't heat up much. In fact, I believe most of what heats it up is the slow loss of antifreeze that comes out of the overflow.
What's strange is that it seems to spew antifreeze out of the overflow at temps that aren't even overheating. At least, that's what it seems. Until finally it slowly spews it out and runs hotter and hotter until it actually overheats.
I noticed my belt is what I would consider very loose now, as though it has stretched. I have it adjusted as tight as I can but I can easily turn the fan with my hand. Would this cause it to overheat at speed? I bought the belt about 2 years ago at a tractor store. It was for an old tractor, but fit close enough at the time.

Thanks,
Brandon

Perhaps you are getting air past the water pump seal. Antifreeze should not be coming out the overflow under normal conditions. Don't overfill the radiator as with a non pressurized system you need to allow some room for expansion. I would definitely install the correct belt, though when loose and slipping there is usually some squealing. Timing can also affect engine temp.

I agree. Take a 1/4 turn on the water pump adjusting nut. This would be the main reason for overheating at speed.

Perhaps that's what's going on. I've tried tightening the packing nut as much as I can until the belt just slips and the fan stays still. Perhaps with a tighter, correct belt, it would allow me to tighten the packing nut to the appropriate amount and the belt would also not slip. I have another belt I had from a parts motor, I'll try and see if it is shorter and if it is I'll put it on there.

Brandon

Also check the bottom radiator hose. If it does not have a spring in it,its possible it collaps under the high RPMs.

I hate to mention the other possibility...a very small crack in the head between one or more of the intake and exhaust valves permitting gases to move into the water circulation system. If this is happening sometimes you will see bubbles coming up in the radiator. Jim

If your tightening the packing nut as tight as you can, till the belt slips, Maybe its time for a new water pump? Just my guess.

Keep in mind that "having the right belt" doesn't just mean having the right length belt. Belts have a bevel angle or pitch that should match the angle of your pulleys. If your tractor belt doesn't have the correct pitch, it could slip at speed and cause your problems. Suggest that you try your local NAPA store or the Filling Station for the correct belt.

Well, I just rebuilt the water pump and put in new packing, so I don't think that's it.

DON'T USE THE "C" WORD WHEN TALKING ABOUT MY HEAD!!!! It's scary.

I'm going to look into the belt. If that's not a problem, I'll move on the the other suggestions.

Thanks guys,
Brandon

I found that "B" size machinery belts of the right length, readily available at farm supply stores fit our old Chevies and other cars of similar vintage and are inexpensive. The "B" belts are wider and deeper than the "A" belts (1/2 inch) usually found in hardware stores.

Another option is the low horsepower belts sold at hardware stores. They have 5/8" wide belts or can get them and the price is reasonable. I have used these low horsepower belts for many many years with long lives and no problems.

I had the same problem with my 32 confederate.
I replaced the waterpump,put all new hoses on, checked the timing,replaced the belt.
I finaly took out the radiator and had it boiled out ( it was plugged at the bottom ), added a thermostat and antifreeze. The car will now idle as long as you want and at all speeds the temp. gauge reads normal

Buckeye

Chipper, I think we're talking about the same thing. "B" size belts are about 5/8" wide. Common V-belt sizes are found at http://www.engineersedge.com/xbelt_size.htm

The Dayco catalog list a number 24380 as fitting 29-32 Chev. It is 3/4 inch by 38" long and the tapered angle is 38 degrees. I am sure most auto suppliers can cross reference the number. Dayco may have been the original supplier for Chev. If you have to tighten the packing nut excessively then there is a problem other than the belt.

Arend,
Yes they are called "B" size belts by some manufacturers or sellers. Others don't. I felt that giving the width of 5/8" was a bit more universal.

The dayco belt is referenced in the archived article. The 24380 cog style of this belt is still sold.


http://vcca.org/members/vccadocs/gd/arti...mp;SearchField=

How long is the belt supposed to be? I can't measure mine because it is stretched.

Thanks,
Brandon

Your local auto parts store (like NAPA) will have the specs. on the 24380 belt listed in an earlier post. Check with them and they will give you the length. You can also find the length of the belt on Google.

Ok, thanks dawg!

Brandon

You bet!

Dayco 24380
Length 38
Outside Circumf 38.64
Top Width .75 (24/32)
Angle 38
Neil G. (Canada)

The '31 uses a 5/8 x 38 inch belt. The late 4 cylinders used a 5/8 x 41 inch belt, actually think it was originally 41.5" but those are not available.

24380 dayco cog style on ebay:

http://www.ebay.com/itm/Dayco-24380-Fan-...=item415cbb3978

Brandon also if you haven't already read the artcle with info on the belt I previously linked it.

its interesting that Bill Barkers 31 site list the chev part number as 836347 and dayco as the mfg. but the belt is too long and also its 5/8 wide. The possibilities as I see them are that it's too long because a 5/8 belt fits deeper in the groove. Second possiblity is that the Dayco catalog size listing of 24/32 (3/4) is incorrect and they never corrected the catalog from initial listing thru the print date I have of 79. I am leaning towards believing their listing is correct. Chipper can you provide your source of informaton that the 5/8 size is correct as my 29-32 Chev manual list only one part number 836347.

Well, this is interesting. I went to NAPA and they had no number for Dayco 24380. They only showed a cross for Dayco 24379.
I went to Advanced, who I found out supplies Dayco, and they didn't have a listing for a Dayco 24380. The guy showed me a L538 that is supposed to be similar.
I also saw the one on Ebay that IS labeled as a Dayco 23480.
Which would you guys recommend?

Thanks,
Brandon

I purchased my 24380 fan belts from my local auto parts store with no problem.

The L538 should be the right belt. L5 would be 5/8" wide and 38 the circumference.

Thanks Chipper. Should I be concerned with the degree of the V inside, or should it be close enough?

Brandon

Do not tighten the belt or the nut outside the gasket as best you can. Too much will result in a broken pump axle. If you hear a sudden loud, squeeking unpleasant (unexpected) noise coming and going when driving, stop immediately and check the belt/axle. If the axle has turned blueish, you have to loosen the belt somewhat.

You can use tractor belts, but the best is newly produced original-sized Chevrolet V - belt.

Well, I wound up getting a lawn mower belt that crossed over from the previously mentioned Advanced Auto belt.
When I went to remove my 4 blade fan to take the belt off, I could EASILY turn the fan with my hand even with full tension on the belt, so it was undoubtedly way, way too loose.
I took a short test drive that included some 40-45 mph driving and it did much better, however it was a short drive (5 miles or so) and it was very cold here today compared to lately (20s or 30s).
I'll try it again later and hopefully it will be OK. I'll have to start from scratch on how much to tighter the packing nut again.

Brandon

Brandon,
Did you get a chance to read this article? There is a part explaining the belt.

http://vcca.org/members/vccadocs/gd/arti...mp;SearchField=

If your Advanced auto dealer who handles Dayco belts could not find a listing then I would find a competent supplier. Go to the Dayco web site and you will find the information you need. A correct length belt that does not have the correct angle will just compound your problems. Also over tightening the packing will burnish it and lessen the chances of it sealing regardless of how its further adjusted and should be replaced.

I called my local Advanced Auto store and they did not have the dayco 24380 belt in stock but can get it in a few days. He also said I could order it on line. just go on Advanced Auto website put in dayco 24380 in search and it comes up.

Aw man. Thanks for the info. After he said he couldn't get it I went across the street to where a friend of mine works at Napa and I ordered a belt that cross referenced the L538. It's a green lawn mower belt, but it seems to be working so far.
I guess I'll know next time.

Thanks,
Brandon

About that green belt...as soon as that radiator boils over again the belt color changes to a nice medium gray...Just part of the make it work set .

Well, I'd say the belt fixed the problem. Got up early and drove to church today, about a 120 mile round trip, and it did fine...except for the VERY last mile of the trip.

Had a little speedometer mishap, but nothing related to the cooling system!

Brandon

I used a can of flat black paint to paint my green belt to Black. I also use the lawn mower belt for my Chevy.