Bertram31.com General Bulletin Board

Re: DILEMMA

Posted By: Vic Roy
Date: Wednesday, 13 April 2005, at 11:18 p.m.

In Response To: Re: DILEMMA (JJ)

JJ - The Cummins 6B's (no matter if it's a 6B natural 150 hp, a 6BT turbo 210 hp, or a 6BTA turbo and aftercooled at 250 or 300) should run at about 185-195 F. depending on sea water temp. Anything over 195 is an issue. Before you start chasing your tail, gat an infrared temp gun and run them at WOT for at least 5 minutes with a good load (I don't have to tell you this, but others may be reading, that means underway, not at the dock) and shoot the engine with the gun to verify what the dash temp gagues are telling you.

The sender to the dash temp gague is located on the top front of the head, so shoot there first and compare with the dash gague. Then shoot the steel expansion tank, which should be within a few degrees of the area around the sender. If you get anything over about 195 in these areas, we need to go deeper.

The usual culprit of overheating in the 6B engines is the raw water pump/impeller. Before you go changing things, let's continue our sea trial at WOT. First, look to see that the offending engine is pumping as much water as it should out the exhaust. If it looks normal or you can't tell, take the infrared gun and let's check the heat exchanger. Under full load, start at the back of the exchanger (cool side, near where the sea water dumps into the exhaust elbow)and slowly shoot towords the front. You should see about a 35 degree F heating from the back to the front. If less, go to the raw water pump, pull it, check the impeller and change it if bad. If it's blown up you have to backflush the whole raw water side and I'll save ya'll that ordeal.

If the pump/impeller looks ok and it's still showing over 195 WOT, maybe time to clean the heat exchanger. Drill is to remove it to the dock, take the end caps off, rod it out with a 3/16th brass rod (alum. ground wire works just as good) then pour acid thru it, a process I'll describe to anyone off site, as this is getting too long.

Bottom line is the Cummins 6B's have a huge excess cooling capacity, and any overheating issues are usualy obvious.

UV

Messages In This Thread

DILEMMA
AL C. -- Wednesday, 13 April 2005, at 12:00 a.m.

I posed a similar question on 1-26-05
STeveZ -- Wednesday, 13 April 2005, at 8:01 a.m.

Re: I posed a similar question on 1-26-05
Tom Annulli -- Wednesday, 13 April 2005, at 9:49 a.m.

More on my experience
STeveZ -- Wednesday, 13 April 2005, at 1:09 p.m.

Re: More on my experience
AL C. -- Wednesday, 13 April 2005, at 5:07 p.m.

Re: DILEMMA
Capt. Dave Kosh -- Wednesday, 13 April 2005, at 10:50 a.m.

Re: DILEMMA
bruce -- Wednesday, 13 April 2005, at 5:12 p.m.

Re: DILEMMA
Vic Roy -- Wednesday, 13 April 2005, at 6:52 p.m.

Re: DILEMMA
JJ -- Wednesday, 13 April 2005, at 10:10 p.m.

Re: DILEMMA
Vic Roy -- Wednesday, 13 April 2005, at 11:18 p.m.

Re: DILEMMA
JJ -- Thursday, 14 April 2005, at 6:28 p.m.

Re: DILEMMA
AL C. -- Thursday, 14 April 2005, at 8:50 p.m.

Re: DILEMMA news *LINK*
a8ecb -- Thursday, 22 June 2006, at 2:11 p.m.