Air Intake Temp

[Dave Carlson]

I know air intake temp can indicate the condition of the after coolers. What values relative to sea temp are considered nominal on QSB/QSC engines?

I have a friend with QSB’s that run 20 deg. over sea temp (100) while my QSC’s run 4-5 deg (86)
over sea temp at cruise. Sea temp was low 80’s on the day we were cruising together.
The QSB’s have issues with performance and are over propped also. Any thoughts on his after coolers?

Topic

[Richard Pietraszko]

Sorry I should have been more specific than just “yes and yes”. Yes, after coolers and heat exchanger were removed from the engine and serviced at the shop, not just some quick cleaning onsite.

[Tony Athens]

You are not answering my question.. Were the aftercoolers removed from the engine for 100% proper servicing off the engine– Meaning on the bench in pieces?

[Richard Pietraszko]

Still no solution

Turns out the coolant was almost two gallons low per motor, topped them off, pressure tested for leaks and still after an of cruising with manifold temps around 130F, it shoots up to 161F (alarm triggers at 155) at idle. Mechanic seems baffled.

[Richard Pietraszko]

Since I’d never got the alarm prior, I have no idea.

Shore Power Solutions, friend of a friend, came highly recommended on the Chesapeake Bay
https://www.shorepowersolutions.net

Yes

Yes

Opposite of what you’d expect, right? And it’s both engines so can’t be one bad sensor.

[Tony Athens]

What were your numbers before the service?

Who did the “service”? Do you know the shop ?

Were the aftercoolers removed from the engines?

Heat exchangers ?

Something sounds screwy..

[Richard Pietraszko]

QSM11 with similar IMT problem

Just had my aftercoolers, heat exchangers done as part of the 1000 hour service. Now whenever I come off plane to idle I consistently get an IMT alarm with temps (on my awesome SBMAR displays) reading 158F. This is on both motors. At cruising speed, 2000rpm, both motors go down to 125F. I loosely confirmed with a temp gun that reads 200F on the intake manifold, at idle. The company that did the work is stumped and coming to look soon but I’m pretty worried. Any ideas? Thanks

[Dave Carlson]

Thanks for the info Tony. I think he is going to look at the props first to get RPM up and fuel burn down where it should be.

[Tony Athens]

Intake Manifold Temperature — IMT

You are leaving out something big–How clean are his aftercoolers internally vs. yours?

As to your actual question– Assuming the complete seawater side of the engine is 100% and the rest of the install is right———-My experience in 65-70F water–Usually the IMT is at about 95F to 110F at WOT making full HP on all the new “Q” engines.. Air in , ( coming off the turbo) can approach 300F or so, meaning a clean aftercooler really drops the temp big time

As to cruise IMT, who know how the engines are loaded, but certainly way less that at WOT..

Tony

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