The Stovebolt Site Forums The Shop Area Engine Shop Car vs truck 235 belts

Issue: have a full pressure 235 (originally from a car). I’m using a duralast 17430 belt. Ive burnt up 2 belts in 3 days.

Discussion: after the first V belt became a flat belt, I removed the belt and used my gun sighting laser to ensure my belts were aligned correctly. What I found was that I need to slide my alternator 1/8” forward to have it aligned almost perfectly. I replaced the belt and went for a test drive. During the test drive, I stopped and rechecked everything and thought I had the belt too tight. I loosened the belt very slightly. (I used a red paint marker to see how far I adjusted everything) when I got home, I found that the new belt doesn’t want to ride in the crank pulley. It was sitting on the front of the lip (just forward of the groove). The water pump numbers are the same car vs truck (same pulley width). The alternator pulley is the same width as a truck 235 (reused pulley from when I rebuilt my 261 and replaced the alternator).

Moving forward: I’m going to slide the alternator slightly back from the original position before I moved it. I’m also going to go the my local flaps to see if a narrower belt (duralast 15430) fits the grove better.


Questions:

Is a car 235 belt width the same as a truck 235 belt?

Are there other things I should consider?

Thanks gents any guidance you may offer.

Chris

Update: I just installed a 15430 belt (15325 belt would fit better) as per what the local flaps stated. It fits deeper into the crank pulley groove. I left all pulleys aligned and did not adjust the alternator back 1/4” like I was going to do. (Using this to document in case I need to look back at this.)

Chris

V belts should ride at the outside diameter of the sheave or slightly above it. They shouldn't sit down low in the groove.

Thanks Otto, that’s what I was tracking hence using the wider belt normally. Im just trying to figure this out.

From your part number, I'm assuming that's a 43" belt. I tried a few different sizes, but settled for a 42.5". Like you, I had to move my alternator bracket forward about 1/4" to get everything to line up.

Chris - I can't remember if you previously posted pictures of your engine, but couldn't find any so hard to say on belt fit without a visual of your pulleys to consider belt width/depth, etc.
It sounds like it will live happier with the 15430 and/or 15425 (I think you typed 15325?) which are generally 0.44" and 0.4375" width respectively.

The only remaining difference between the 15430 (43.0" overall length) and the 15425 (42.5" overall length) result in your alternator standing up a little taller and closer to the engine center line using the slightly shorter belt.

I recall John posting about searching for the right length belt as I think his alternator leaned too far outboard.

Gdad,

I’m not so much worried about the length, as I can figure that out. (You are correct with the typo) I will need to go with a shorter belt. Biggest issue is the belt width.

Are the 15000 series belts the correct width?

Chris - I did a check in various Chevy Master Parts Books. The 1962 Book (see screenshots below) probably has the most detailed listing of the various belts for your 3 pulley setup, depending on the original application.

I think the majority of the applications, including the 261 (depending on year), indicate the most common belt width is a 3/8" (0.3875"). That might put the 15000 series belts just a touch wide as the majority of those I scanned through ranged from 0.41" to 0.44" wide, which is more of a 7/16" (0.4375") wide belt.

I'd get a 3/8" wide belt, 42.5" O.L. like this Duralast piece and see how it sits in the pulley grooves. As long as the bottom of the belt doesn't ride on the bottom of the pulley grooves, that will likely be your best fit and the one to stay put in the grooves when running.

That's actually the belt I have!

Update: I’m currently changing out the alternator pulley so it’ll be back to the thinner belt.

More to follow!

Gdad,

Thank you! That is what I was trying to find out!

Chris

Morning update:

I placed the 15000 series belt (narrow belt) on the 235 and the belt bottoms out on the. Water pump pulley and squealed like a pig. (I can demonstrate if needed. 😂) we noticed that the belt fits perfectly in the alternator and crank pulleys, but moves front to back in the water pump pulley.

I put a new wider belt (17000 series) back on and no squealing. The belt fits into the water pump pulley and fits into the alternator pulley, but sits slightly higher in the crank pulley.

I’m going to my flaps to check out the belt GDAD stated earlier (maybe it’s in between sizes?

The water pump is the correct 1954 235 water pump. So the question I have now is where do I go from here?

A V belt sitting on the bottom of the groove will slip and wear out fast. Belts need to sit flush or slightly proud of the groove.

From your description, it looks like the 17000 belt works fine. What more is there?

Chris - It sounds like your water pump pulley may be for a slightly wider belt (1/2" or even5/8" ???) than the alternator and crank pulley. The belt should fit similarly in that water pump groove as it does in the other 2.

Would be super helpful for everyone if you could post pictures of the fit of belt in each pulley. Going back to the lists I posted above, for every different width belt, there are corresponding different width pulleys. It's very easy to get a mismatch.

Let me figure out how to make them smaller with my phone

Added: I will attempt to make 3 separate posts. 1 with wide belt pictures, 1 with narrow belt pictures, 1 with the V belt you told me to try.

It’s too hot outside and the metal is hot to the touch.

This is the 15000 series Duralast belt (0.44” wide) each pulley is labeled and you will see the water pump pulley is slightly different then the stock “car” water pump. (I was told they are the same numbers at my local flaps.

Here is the 17000 series duralast belt (0.51” width).

Sorry if belt isn’t perfectly aligned as I was holding a camera, index card and the belt while trying to get a clear picture.


*** I will update with more pictures when I get the V Belt that GDAD recommended. I hope this helps someone.

Water pump needs a wider belt or a narrower pulley.

Dayco Top Cog CQD 3300079

Otto,

I agree with you. I never would’ve thought that there were different water pumps for a 235 (car vs truck). I just purchased a new water pump because that’s exactly what I want to do in 112 heat index! 😂

I might attempt to pull off the pulley on the old pump, but I’m guessing it’s not coming off without a fight

Chris definitely a mismatch with that new water pump pulley. Actually looks to be a 5/8" wide piece, which is a common size for the early engines. The majority of flaps just take the rebuilders word for what the pump fits, with no real attempt to accurately match the pump casting and/or pulley.

We as buyers are stuck with trying to coerce them into finding the right parts to match the item it's replacing, usually requiring visual side by side comparison. Your old pump pulley may seem likes its stuck and unmovable, but I'm confident you can encourage it to release from the pump hub and transfer it to your new pump.

In the photo, your alternator looks like it’s sitting off line from the belt. Make sure all your pulleys are for the same belt width. When installing a belt, tighten belt, then rotate the crank and check tension again in different spots.

I think he's just holding the belt in position for the photo so it isn't really lined up properly.

Rusted Nut,

The pulleys were aligned using a laser and they are extremely close. The belt in pictures was not straight due to holding too many things while taking pictures.

Update: I decided to purchase a new water pump AND confirm that it has the correct pulley. I was unable to remove the smaller fan blade on the original “car” water pump, so I’ll try a few more things before I give up.

What I’ve learned-

1. A 235 water pump is not a 235 water pump (car/truck are different)
2. Never trust a Flaps
3. V Belts can run from 3/8 to 1/2” on most 235
4. Duralast 15000 belt is 0.44”, 17000 belt is 0.51”
5. Inspect before you install! (OPS!)
6. When in doubt ask a brother (Stovebolt.com)

Thanks guys! I’ll post more once I get the new pump.

Chris

New water pump fits great! Pulleys are aligned, belt and fan in place! I will connect the hoses and fill tomorrow.

Here’s to no leaks! Cheers!

Chris

And it looks like they're all riding in the sheaves correctly, too.

What width belt did you end up with, half inch. 7/16, or 5/8?

Everything is back together, test drive completed, no more squealing belt, and no leaks! She sounds better than when I got her!

I used the Duralast 15000 series (0.44” width). I also have a 3/8” wide belt on standby.

Chris

Thanks you everyone!