454 1 manifold hotter than the other

[kitacooch]

Hey there, i am running twin 454's and the starboard engine has 1 manifold heating up much more quikly on idle and ends up a lot hotter at running temp.
The starboard engine is also hotter overall than the port engine, port 350 degree F and and starboard 390 degree F.

Everything seems fine externally, am i missing something?? has this happened to you??

thanks

 

[Bondo]

Re: 454 1 manifold hotter than the other

The starboard engine is also hotter overall than the port engine, port 350 degree F and and starboard 390 degree F.

Ayuh,... Those temps are awlfully hard to believe, as water boils at 212?....

Rebuild yer waterpumps with new impellers...

 

[HT32BSX115]

Re: 454 1 manifold hotter than the other

Ayuh,... Those temps are awlfully hard to believe, as water boils at 212?....

Rebuild yer waterpumps with new impellers...

Yeah. and after you do that, pull yer oil coolers and clear out the impeller fragments from the previous impeller failures......


Then, have a look at the manifolds and risers. If they're rusty enough inside they'll restrict flow enough to cause overheats.....


My oil cooler was so plugged with impeller pieces it's amazing the engine didn't over heat immediately!!


Also, if your boat also has OMC Cobras installed, (god help you!) you should also ensure that the entire raw water path is clear of impeller fragments all the way to the t-stat housing(s) and heat exchangers (if installed)

And if heat exchangers ARE installed, check them for blockage too. most closed-cooled engines have heat exchanger discharge going directly to the exhaust manifolds/risers (1/2-system) or risers only (full-system)


Cheers,


Rick

 

[kitacooch]

Re: 454 1 manifold hotter than the other

MMM maybe didn't get conversion right, am running 175-180 degree celsius on port and 200 on starboard at plane but not flat strap, i feel the starboard would get hotter but feeling 200 would be the limit before things go bad.
am running fresh water with heat exchanger, all new to me, the manifolds are "hi-tech" aussie made stainless and are pretty new and clean as a whistle, the heat exchanger seems clear with regards to flow in both fresh and salt side, my feeling is that maybe not getting enough salt water so am planning to replace impallers on pumps
not familiar with the oil cooler didn't notice one will investigate this, am guessing this has a heat exchanger type setup, salt water cooling the oil??? but where??

 

[HT32BSX115]

Re: 454 1 manifold hotter than the other

am running fresh water with heat exchanger, all new to me, the manifolds are "hi-tech" aussie made stainless and are pretty new and clean as a whistle, the heat exchanger seems clear with regards to flow in both fresh and salt side, my feeling is that maybe not getting enough salt water so am planning to replace impallers on pumps

Ok....So you're running a 1/2-system. Those SS bat-wings (that cost a fortune!) are cooled by "RAW" water

Your heat exchanger is cooling the BLOCK only.

It doesn't take a LOT of cooling capability to cool an engine block. BUT if you don't have enough raw water FLOW through those manifod/riser combo's they'll get pretty hot.

If they're getting too hot, there'll be a LOT of steam. salt water boils at a slightly higher temp than fresh water. (a few degrees......104*C maybe) well within the experimental accuracy of your gage.

my feeling is that maybe not getting enough salt water so am planning to replace impallers on pumps

YOU SHOULD CHANGE THE IMPELLERS FIRST when you suspect any sort of cooling problem and they've not been replaced!

You still haven't indicated if this is an inboard or a Cobra outdrive boat.

If it's Cobras, The impellers can fail and partially disintegrate....(and still pump some water) Pieces can be "stuck" anywhere in between the pump discharge to the oil cooler and on to the heat exchanger.

Oil coolers are usually cooled with raw water as are the power steering coolers (if installed)

 

[kitacooch]

Re: 454 1 manifold hotter than the other

Ahh, steam, it's all coming together now, i pulled the manifolds off and learned about them filling up with salt water and so on, they all good, sorry it's a crash coarse for me, have only had boat out a couple short trips while fixing everything, lets not got there, but anyway i felt that both engines but in particular the hot one were steaming up out back, did the sniff test/colour, seems to be steamy rather than fumey so guessing this coming from manifods running too hot therefore not enough water running through them therefore raw water pump sounds suspect. What next?? Will get them sorted and go from there.

Hey cheers for your help much appreciated.

 

[kitacooch]

Re: 454 1 manifold hotter than the other

Ok, impellas are like brand new, so ruling them out, has been suggested i hook up some clear hose and look at/compare water flow on both manifolds so i guess will try this.

Can someone confirm if i need to prime the raw water pump/pickup once i put it all back together??? If so how would one usually do this??

cheers

 

[Bondo]

Re: 454 1 manifold hotter than the other

Can someone confirm if i need to prime the raw water pump/pickup once i put it all back together??? If so how would one usually do this??

Ayuh,... Either put the Muffs on it, or the boat back in the water...

 

[HT32BSX115]

Re: 454 1 manifold hotter than the other

Ok, impellas are like brand new, so ruling them out, has been suggested i hook up some clear hose and look at/compare water flow on both manifolds so i guess will try this.

Can someone confirm if i need to prime the raw water pump/pickup once i put it all back together??? If so how would one usually do this??

cheers

There's no priming required if the boat is in the water. The raw pumps will be practically under water.

 

[kitacooch]

Re: 454 1 manifold hotter than the other

Ahh yes, so they will.

cheers for that

 

[HT32BSX115]

Re: 454 1 manifold hotter than the other

Ok, impellas are like brand new, so ruling them out, has been suggested i hook up some clear hose and look at/compare water flow on both manifolds so i guess will try this.

If you have had impeller failures in the past, don't forget to check for obstructions (impeller fragments, debris, or other "stuff") in the raw water supply lines and T-stat housings etc to the engine(s).