1994 V-4 Looper E120TLERC Cooling Problem

[sportpilot]

Hello to all and before I begin, let me say thanks and glad to be aboard...I have spent the last week reading through posts and obtained a wealth of information about my new boat and motor...many thanks to all!!

I've got this engine mounted on a 1996 Stratos 278 with a Viper 13 7/8 X 19 SS Prop. Running about 48.3 mph without a jack plate. When I bought the boat, previous owner was running a 13 1/2 x 22 SS Raker. It was taking 3-4 boat lengths to get on pad and running about 5200 PRM at the same speed. I put on the lower pitch and got a great hole shot with about 6000 RPM. Now I have an overheat problem...

Engine is strong and runs great at idle and on the top end, but goes into SLOW mode before I can get anywhere. I have read on here that this limits RPM to 2500, but I can maintain 3500 before it starts cutting out...is this normal for this engine? Either way, running on Toledo Bend here in East Texas, that isn't going to cut it...

The stream coming out of the aspirator is steady, but not strong...and is typically in the 125 F range (verified with thermometer). Should the water be this hot? The previous owner told me that this was common for this engine, but the stream seems weak to me. At idle, I am averaging about 4 psi and at 5500 RPM, the water pressure gauge is pegged at over 30 psi. I am assuming that the water pump is alright, but I have ordered a new one from BRP along with new thermostats and a new screen for the intake. My question is this...I have pulled the plugs and looked in the cylinders with a light and none appear to be "steamed" but going to pull the heads and verify while I have it down. While I am doing all this, is there anyway to "flush" the water channels to ensure I don't have a blockage between the water pump and the power head? If so, what do I need to avoid doing to prevent blowing out a seal somewhere else?

I am going to pull the two sensors tonight and verify that they are opening and closing at the correct temperatures and will report back, but just want to get some other insight into this problem as I get started...

Thanks in advance...

 

[Dhadley]

Re: 1994 V-4 Looper E120TLERC Cooling Problem

Does the hot horn sound at all?

 

[sportpilot]

Re: 1994 V-4 Looper E120TLERC Cooling Problem

Not sure if this boat is equipped with a warning horn...I have never heard an audible warning, but it does have the OMC guage set up with the 4 idiot lights in the tach...and yes, the HOT light does come on when it goes into SLOW mode.

 

[HighTrim]

Re: 1994 V-4 Looper E120TLERC Cooling Problem

That motor is definately equipped with a warning horn. Grounding out the TAN temp wire to the block should cause it to sound. If it is faulty, I would get it fixed ASAP.

When changing a water pump, I always like to flush the cooling circuit while I have the lower unit down. Remove 1 t stat at a time, then run the garden hose, or compressed air up the water line to the t stat housing, and then backflush down. Install new t stat, remove second, then follow same procedure. This will ensure there is no debris restricting water flow.

Regarding the SLOW mode, verify that the engine is not overheating.
Then disconnect the TAN temp wire from the pack. If all is now well, replace the temp switch. Also make sure the TAN temp switch wire is not located next to a spark plug wire.

 

[sportpilot]

Re: 1994 V-4 Looper E120TLERC Cooling Problem

Thanks HighTrim...

I pulled both temp sensors last night and tested. Just immersed them in some oil while heating up on the stove, but both closed at ~ 197 F and then opened back up just past ~ 180 F on the way down. I reinstalled them in the block and grounded out both tan wires to the block seperately and got the HOT light each time, but no audible horn. I got up under the console and found a klaxon type horn with a purple and white wire going to it...assume this is the warning horn. Hit it with 12V and got nothing, so going to get a replacement this afternoon.

I do know it is overheating and my primary concern is what is causing it...hopefully will find something plugged when I pull the thermostats out and take a look at the water pump this weekend...