One riser 60 degrees hotter

[hoodooman]

I just completed a single piece batwing to two piece wet joint conversion on my 1998 4.3 i/o raw water cooled bayliner. I used all mercruiser parts including the graphite style riser gaskets. Prior to this, I also installed a new impeller, which I've done numerous times. Buttoned up the install today and fired the boat up on muffs in the yard. I ran it at about 2k rpm for maybe 15 minutes. The starboard side riser was 60 degrees hotter than port(150 vs 90). what's interesting is that the boat is slighly canted to the starboard side, but there is much more water shooting out of the port side, which is the cooler side. The boat seemed to run well, but I shut it off due to the riser temperature. the temp gauge on the boat stayed right where it normally does, 170 or so.

when shutting it off, it dieseled, which it's never done before. i saw some steam coming out of the starboard side exhaust. These are all new parts and i can't imagine what i did wrong. do i need to take it to the lake to really see how it does? i REALLY took my time on this job and was very thorough.

there was definitely water coming out of the starboard side, but not much compared to port.

what should i troubleshoot? thanks! this was a HUGE time and money investment.

 

[Scott Danforth]

Never run faster than 1500 RPM on muffs

Since your trailer is never perfectly level, the higher elbow will be hotter

 

[hoodooman]

Never run faster than 1500 RPM on muffs

Since your trailer is never perfectly level, the higher elbow will be hotter

I appreciate the info about rpms. The lower side was the hotter side, which is perplexing.

 

[Pmt133]

Just out of curiosity, which thermostat housing do you have and which gaskets did you use between manifold and elbow? There are a few different configurations and combinations to account for. Though those temps don't seem out of line...

 

[Bondo]

I appreciate the info about rpms. The lower side was the hotter side, which is perplexing.

Ayuh,...... Welcome Aboard,....... Both sides, rarely to never run the same temps,.....

 

[hoodooman]

Just out of curiosity, which thermostat housing do you have and which gaskets did you use between manifold and elbow? There are a few different configurations and combinations to account for. Though those temps don't seem out of line...

The thermostat housing has the plastic sleeve with a 160 thermostat. I used the silver graphite infused full-flow mercruiser gaskets on the risers.

 

[hoodooman]

Ayuh,...... Welcome Aboard,....... Both sides, rarely to never run the same temps,.....

Thanks for the info. is a 60 degree variance normal? this is the only boat i've ever owned, and it had the batwings previously which didn't have that big of a variance in temperature.

 

[Bondo]

The thermostat housing has the plastic sleeve with a 160 thermostat. I used the silver graphite infused full-flow mercruiser gaskets on the risers.

Ayuh,........ We need more info on yer motor, as most run the restricted flow gaskets,.....

 

[hoodooman]

Ayuh,........ We need more info on yer motor, as most run the restricted flow gaskets,.....

Sure thing. What info would be helpful? I purchased the parts through powerboatsupply and they suggested the full flow gaskets. it's a 1998 4.3 vortec 2bbl (0L072138 serial). The kit i purchased for the conversion also comes wiith full flow gaskets. I have an alpha one gen 2 outdrive. thanks!

 

[hoodooman]

 

[Pmt133]

I think, according to bulletin 99-10, those would be the correct gaskets for your application and thermostat housing.

 

[Lou C]

I did a similar conversion on my 1988 OMC 4.3 and didn’t see that big of a difference in temps, my starboard might be 95 at idle and port like 80*. Now after running out on the water both are higher but maybe like 135 stbd and 120 port after coming off plane. After idling for a few min it’s like 115 and 100.
I would:
Disconnect both manifold feed hoses and briefly start the engine to see if flow on both sides is approx equal. If not investigate further.
Also is it possible an exhaust flapper is sticking shut holding hot water in the exhaust system longer on that side? The idea is to have close to = flow in and out…

 

[hoodooman]

I did a similar conversion on my 1988 OMC 4.3 and didn’t see that big of a difference in temps, my starboard might be 95 at idle and port like 80*. Now after running out on the water both are higher but maybe like 135 stbd and 120 port after coming off plane. After idling for a few min it’s like 115 and 100.
I would:
Disconnect both manifold feed hoses and briefly start the engine to see if flow on both sides is approx equal. If not investigate further.
Also is it possible an exhaust flapper is sticking shut holding hot water in the exhaust system longer on that side? The idea is to have close to = flow in and out…

Thanks for the troubleshooting idea, i'll check the flow. The flapper issue is possible. They are original, but seemed just fine when I had the exhaust apart. Boat has low hours, maybe 75 hrs.

 

[cyclops222]

My 2002 5.0L had a coolant ....Balancing Valve...To help both sides be the same temperature. My old mechanic removed the valve. Because they were known to stick either way. Temperature difference was about 10 F all the time.

 

[hoodooman]

I did a similar conversion on my 1988 OMC 4.3 and didn’t see that big of a difference in temps, my starboard might be 95 at idle and port like 80*. Now after running out on the water both are higher but maybe like 135 stbd and 120 port after coming off plane. After idling for a few min it’s like 115 and 100.
I would:
Disconnect both manifold feed hoses and briefly start the engine to see if flow on both sides is approx equal. If not investigate further.
Also is it possible an exhaust flapper is sticking shut holding hot water in the exhaust system longer on that side? The idea is to have close to = flow in and out…

I took both hoses that go to the manifolds off and started it up for a minute or so. Interestingly, the flow to the HOT side is getting 80% of the flow. The cool side didn't have much water flowing out. On the trailer, using a level, the side that is cool is up higher than the cool side. perplexed. I think I need to take it to the lake to see how it does.

 

[Scott06]

I took both hoses that go to the manifolds off and started it up for a minute or so. Interestingly, the flow to the HOT side is getting 80% of the flow. The cool side didn't have much water flowing out. On the trailer, using a level, the side that is cool is up higher than the cool side. perplexed. I think I need to take it to the lake to see how it does.

Yeah I wouldnt worry too much unless it gets to hot to leave your hand for a few seconds.

 

[cyclops222]

Exhaust manifold gasket leaking ?

 

[hoodooman]

Sea trial was a complete success today. Starboard side riser never got over 120 degrees out on the water. Port side never got over 83, but I hear that's normal. Infrared gauge confirmed all temps including block temp were steady and within spec. Turned out great, thanks!