Water coming through the carb

[Val V]

The block of the engine was rebuilt and a used (newer than older) head was put on and torqued by the shop. I put on the rest of the parts including manifold and the carburetor. I am starting the engine for the first time and while cranking water started coming out of air intake of the carburetor. I took the carb off and put a cup under manifold intake. Continued cranking for another 10 seconds or so and I got little less than 1/4 of a cup with water.

Do you think the manifold is gone or could there be other possibilities of a problem?

Is there a way to rule out manifold for sure?

[Mo]

Hi Val,

You can pressure test the manifold but that's allot of water to be coming out during cranking...so there's probably an easier test for you in this circumstance.

1. Remove all the spark plugs..look for water droplets on the plugs...remember where they came out from. There could be water on one or two or all of them depending if the manifold is broken from frost or major rust etc.
2. Remove the hose coming from T stat to Manifold at the manifold.
3. Blow into the nipple on the manifold (where you took the hose off) and listen for air in the head where you removed the spark plugs.

This sounds like a major leak so you should easily hear air in the head. I diagnosed mine like that in 2007 when I bought my boat.

[hanleyclifford]

Was the water intake thru hull open during cranking?

[Val V]

Was the water intake thru hull open during cranking?

This was in my garage. So no thruhull but the hose was in a bucket of water, which I guess would be equivalent of fully open sea cock.

[Mo]

Good point Hanley. Val, leave the water hose out of the bucket until the engine starts then stick the hose back in the water...if the engine stalls right away likely manifold shot. Do you have a T-stat in that engine right now? Need to check oil for water now as well, OK.

[Val V]

Good point Hanley. Val, leave the water hose out of the bucket until the engine starts then stick the hose back in the water...if the engine stalls right away likely manifold shot. Do you have a T-stat in that engine right now? Need to check oil for water now as well, OK.

No T-stat. By pass half open. I looked quickly in the transmission and didnt see oil milky. Will run these tests tomorrow!

[Val V]

No good news yet. Removed water from the equation completely but still engine would not start other than few isolated pops.

Removed each plug and tested spark on each of them.
Checked oil and cylinders for water. All is clean.
Fuel is definitely going in the carb but I have no sure way of knowing its going inside the block.

So what about this theory? When water was on, it was coming through the carburetor and on the floor. One might think the mani is shot. So IF there is a hole in the manifold, could it stop the fuel from getting into the block ???

Should I get a can of starter fluid and just spray in the manifold intake?

Val

[Mo]

No good news yet. Removed water from the equation completely but still engine would not start other than few isolated pops.

Removed each plug and tested spark on each of them.
Checked oil and cylinders for water. All is clean.
Fuel is definitely going in the carb but I have no sure way of knowing its going inside the block.

So what about this theory? When water was on, it was coming through the carburetor and on the floor. One might think the mani is shot. So IF there is a hole in the manifold, could it stop the fuel from getting into the block ???

Should I get a can of starter fluid and just spray in the manifold intake?

Val

If the manifold is shot is will have difficulty starting or may not start at all. The water would mix with the fuel and actually put the fire out...therefore no combustion. There may be drops of water on the plugs...gas doesn't leave drops. No starting fluid...don't need it...we fix what is going on there.

Check: Air, Spark, Fuel and Compression for it to run. Just do the quick blow into the manifold with the plugs out to see if there is a major leak.

[ndutton]

Can we get a manifold pressure test please? It's time.

[romantic comedy]

This is the only place I have ever heard of "manifold pressure". I know it actually is a pressure, but every gauge I have seen, calls it vacuum.

Texts cal it vacuum. if we had a supercharger, then it would be pressure.

just curious as to why

[Mo]

This is the only place I have ever heard of "manifold pressure". I know it actually is a pressure, but every gauge I have seen, calls it vacuum.

Texts cal it vacuum. if we had a supercharger, then it would be pressure.

just curious as to why

Because we block both ends and pressurize it. I think!

[ndutton]

Mo is correct. Close off the manifold water jacket with a Schrader valve and gauge, pressurize to [fill in preferred test pressure here] and see if it holds the pressure. This will determine if there's an internal breach of the manifold water jacket (the suspected source of the water).

[Val V]

First couldnt find it but google helped. so its schrader to 1/8 and then i guess i would get a step up to 1/2.

Thanks will report back today.

[ndutton]

Whatever it takes. Some guys thread it all up, others use inner tube remnants clamped in place. Remember Home Depot has a test assembly for $10 in their plumbing dept.

[Whippet]

pressure test set up

Here is how i did mine.

Bike tire pump w integrated pressure gauge. Schrader valve from auto parts store. Clipped off mushroom end and clamped into 1/2" hose. In photo, follow red hose. This photo was block test, but manifold same principle. (i also dipped pump assembly into water to make sure no air leaks).

Tried Home Depot gauge first, but my hose barb didnt thread cleanly (must have been a NPS vs NPT thing) so took it back.