VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 1929 Chevrolet Test Drive after Engine Rebuild - Air in Coolant

got some free time this weekend, and went through and reset & adjusted the brake system

ensured everything was secure and decided to take it out for initial drive around the block. drive went well, rode fine, accelerated and braked nicely. One thing i noticed was as the engine revved up there was air in the coolant. hoping it was an air pocket, but it never went away. only drove about a 1/2 mile or so around the block. when i got home check gauges and used my temp gun, everything was in range. i shot a small video of the issue, at idle seems to be fine, but when revved up or running you can clearly see the air bubbles !! and at higher revs ay 1200 - 1500 looks like carbonated water !!  also the whine is easily heard and increases with the revs of hte engine. 

used my stethoscope and seems like it is coming from the water pump, this is a Brand New out of the Box water pump, bearing type. i went back over the engine, tightened all the hose clamps, retorqued the head, it has been through several dozen heat cycles. and still issue persist. 

i plan to remove the drive belt and see if the whine goes away. 

wondering IF they air could be sneaking in past the water pump shaft/seal ? there are no visible traces of coolant leaking anywhere.

1929 Chevrolet International AC - Water in Coolant

Hello BearsFan315,
Harbor Freight
(Maddox: Combustion Leak Detector) and
(Block Tester: Combustion Leak Detector Fluid)
Question? Can you detect any blow-by pressure at the radiator fill nozzle/overflow pipe? Just for fun, zip tie on a plastic bag and see if it expands.
I have read that thermostats are not recommended on the 194 engine.

Jerry, read my reply on the AACA forums.

Hello BearsFan315,
Chistech explanation makes sense. Can you watch the coolant level in the radiator while the engine is revved to verify that the level does drop enough to allow air into the tubes? Does this present a problem? Do you need an overflow tank so as to fill the radiator to the max? Don't know. Is your radiator core new with good flow or old with restricted flow?

are their tubes in the honeycomb radiator ?? did not think there was based on its design.

per my rebuild posting the radiator has been cleaned, flushed, leak tested, pressure tested, even top coated black by the local old school radiator shop.

went out and removed the generator and drive belt and ran the engine for a few minutes. the whine is there, so it is NOT the water pump NOR the generator. sounds like it is coming from the front end, trying to track it down with my mechoscope (mechanics stethoscope)

I would suspect it is from the timing gears.
What will cause them to whine for sure is just replacing the fiber gear and not the steel gear. The old fiber gear wears a pattern into the teeth of the steel gear, causing a whine, that usualy gets less with wear. Also the gears running with no oil can cause them to whine (and fail)

they did a new aluminum timing gear (TFS RW-593A) with a new steel crank gear (Gary Wallace)

I expect that the aluminum gear running on the steel gear is the source of the whine. There was a good reason Chevy used a fiber gear - noise control.

Aluminum gear....that is your problem and the reason Chevrolet only used the aluminum gear in heavy duty trucks.

A fiber gear, if it is getting oil, will last for 100,000 miles.

yeah, i figured, issue was finding and getting a 1929-32 fiber timing gear was a no go. could not find one, and waiting around 6 months. ordered one but was not a 1929-32 was later year.

all of this is in my build on here

so looks like the whine is fine and not an issue?

It may very well quiet down a good bit as it wears in....I'd say run it and see what happens.

All the Best, Chip

It will be fine as long as it is GETTING oil.
On a truck that i had the gear made noise when cold but as the oil warmed up it got quieter.
The major cause of fiber gear failures was the oil feed pluged up with sludge and the gears ran dry and failed.
On a pre 1949 engine the timing gears were gravity fed and cold oil took a while to flow through the small openings.

I also had air in the coolant on a rebuild. had to burp it squeezing the radiator hoses with the engine running and the radiator cap off. cleared up instantly

If you are like the rest of us, you probably have ended up with some parts from a few different years around our target year. (You know '28, '29, '30, '31, they were all just OOOOLD Chevy parts looking for a new home. You can tell by the lonely little bowtie cast, or stamped into it.) One thing I have found is that the timing gear covers and oil slinger combination for 1929 are unique to that year. It is only a little bit but by mismatching from 1930 to 1929 the oil slinger will rub on the inside of the timing gear cover. Not sure if that is your noise but by using the tube one of the other members mentioned as an ear piece you should be able to tell if that is even close to where it is coming from. If you do decide to pull the lower pulley the oil slinger will be loose in there. If it is tight and won't rattle with a screw driver then you will have to pull the cover too. Unfortunately that will entail pulling the pan as well because the 3 lower bolts are from the inside.

From my experience the actual gear noise is more like a growl, a lower pitched noise. Maybe it gets higher with a higher engine speed. But aluminum can transmit noises differently so who knows.

I was given a lower pulley puller from the zone warehouse designed for 1928, and 1929 Chevrolet with the radiator still in the car. The bolt is about 18" long. Sometimes it is very handy. If somebody in your region has one it might make some of your research a little easier.

Keep the forum posted as to what you find.

Art