Bypass balls ? (on t-stat housing) BBC

[inbetween]

What's the purpose and are they necessary?

Idled the boat on the lift yesterday, One set of tailpipes was cold to the point of condensation (air temp 80, water temp 45 ish) the pipes on the other were warm, not hot, just warm. I leaned on one for several minutes while the engine was running. N?ot sure if one engine is getting too much water to the exhaust, or the other not enough?

Running Gil Offshore manifolds with dry tails.

Thanks

[DAREDEVIL]

What's the purpose and are they necessary?

Idled the boat on the lift yesterday, One set of tailpipes was cold to the point of condensation (air temp 80, water temp 45 ish) the pipes on the other were warm, not hot, just warm. I leaned on one for several minutes while the engine was running. N?ot sure if one engine is getting too much water to the exhaust, or the other not enough?

Running Gil Offshore manifolds with dry tails.

Thanks

Could be a lot of things, did u check the timing ..is it 100% the same on both engines ??
Heat has not just to do with water !!!

[MOBILEMERCMAN]

What's the purpose and are they necessary?



Thanks

Adam, Those act like dump valves in part. They help guide the water thru the manifold at lower rpms. As flow increases they dump. I suggest you do not mess with them. It is not uncommon for there to be a slight variation in tail piece temps. Have you replaced your impellers recently? Do they flow water evenly out the back? A minor obstruction in the tail piece outlet can reduce flow and increase the temp also. Water will take the path of least resistance.

[inbetween]

Could be a lot of things, did u check the timing ..is it 100% the same on both engines ??
Heat has not just to do with water !!!

That's a good question...I'll recheck the timing to make sure it's the same.

Adam, Those act like dump valves in part. They help guide the water thru the manifold at lower rpms. As flow increases they dump. I suggest you do not mess with them. It is not uncommon for there to be a slight variation in tail piece temps. Have you replaced your impellers recently? Do they flow water evenly out the back? A minor obstruction in the tail piece outlet can reduce flow and increase the temp also. Water will take the path of least resistance.

Too late, I did mess with them, before I changed the exhaust. With the stock Merc exhaust, one pair of tips was 40 or so degrees warmer than the others, I compared the ball adjustments side to side and one was tightened almost as tight as it could be. I set them to the same length, bolt head to nut length. That seemed to reduce the temp differences. Impellers get replaced at least yearly. I do have different pumps. One Merc plastic housing, one Jabsco brass housing. One impeller has more blades than the other. Water flow out the back is slightly lower on the warmer side. All four water dumps, one for each manifold/tailpipe, seem to flow at slightly different rates.

Engine temps with mechanical gauges at the t-stat housings both read the same -155-160 when warmed up. I'm running 160 deg thermostats.

[MOBILEMERCMAN]

Too late, I did mess with them, before I changed the exhaust. With the stock Merc exhaust, one pair of tips was 40 or so degrees warmer than the others, I compared the ball adjustments side to side and one was tightened almost as tight as it could be. I set them to the same length, bolt head to nut length. .

That's OK. A better response from me would have been not to remove them.

I would be more concerned with the temps at speed then at idle.

[US1Fountain]

Those aren't bypass balls. They are check valves. Test them just to see how restrictive they are for passing water. You'd be surprised there is almost no restriction. The springs just keep the balls in location. They do bypass water past them when running at speed, but their main purpose is to prevent the hot water from the ex. manifolds going back into the motor.
It's a balancing act the involves pressure

[inbetween]

I would be more concerned with the temps at speed then at idle.

After 35 miles at 3500-3800 rpm, the tail pipes are all between 110 and 120 degrees. Guess I won't worry too much about the idle differences.

Thanks

[ElvisAaron]

yes it is great..
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