Engine temps ???

[mphatc]

A technical challenge . . .

Set up is a Bravo and a H&M 302 cooling system, original Jabsco pump crankshaft driven with a new Globe polyurethane impeller, new thermostat.

Running on the trailer with a garden hose at 35 PSIG and muffs coolant engine temperature runs at 175 -180

Sitting at the dock at idle temp will barely go over 120 indicated

Running on the water it will barely reach 115 indicated

( in both above situations the engine operating temps measured with an infra red gun are much higher. Closer to 200 degrees)

At initial dyno runs in 45 PSIG water pressure, no Jabsco pump, same t-stat, 180 degree water temp

Same water temp sensor in every application . . . .

Mario L.

[mattyboy]

Mario,
just i thought could it be the reversed risers??
my 351w setup runs just the opposite on a hose 110-120 on lake water 175-190( season lake water temps 70-85 degrees)

[Schnook]

Compare your water inlet temps (lake water vs hose). Engine might not have a chance to heat up.

[MOP]

Mario were the infra red readings taken while the engine was at running RPM's or right after shut down ?
The reason ask is I can't tell you how many times new customers came in with what I call "False over heat" when nothing was actually wrong! This only happens on raw water cooled applications as cold water is being supplied directly to the block, when the flow is stopped or slowed to idle the cold water drops to the low points in the block forcing the hotter water up by convection giving a false reading. I have seen an average fluctuation from running at 160 going to near 200 at low idle or by turning the key back on after shut down. Another thing to check is a possible wrong temp sender it could be for a dual helm install I would check the number, they will read quite a bit lower not having to supply resistance ground to two gauges.

Phil

[mphatc]

Thanks for the thoughts . . but with this info you might find it even more baffling

reversed risers . . water passes thru these after leaving the engine block . .

temp sensor is new and is the matching unit to the new gauges in the boat

garden hose temp is 55 degree artesian well water, lake was 65-70 degrees

infra red temps were measured at the block right after a hard 2miles run, at the dock, while the engine was still idling, so there was no time for heat soak . . .

I am concerned as this may also have something to do with the wearing out of the engine besides the machine shop F%$K ups, all after 30 hours running! As I am about to spend another chunk of money to build it again with some more power and greater rpm potential

Mario

[MOP]

Quotes!!

infra red temps were measured at the block right after a hard 2miles run, at the dock, while the engine was still idling, so there was no time for heat soak . . .

when the flow is stopped or slowed to idle the cold water drops to the low points in the block forcing the hotter water up by convection giving a false reading. I have seen an average fluctuation from running at 160 going to near 200 at low idle or by turning the key back on after shut down.

Mario we found readings must be taken at running RPM's static or underway, you must have good block flow. I have seen gauges rise in the short time it takes to throttle down entering a channel. It happens a lot more quickly then you can imagine, it takes a little while for the flow to even out the temp at idle.

[BUIZILLA]

Mario, have you been able to determine exactly what happened to the engine and why ??

JH

[mattyboy]

Mario,
I guess my point was with the risers in a normal install they are pointed slightly down hill towards the exit the back of the boat sits lower in your app they are probably slightly uphill which will give the water leaving the block some resistance slowing it down keeping in in the block longer letting it heat up more???

[mphatc]

Buizilla, not yet, disassembly is planned shortly. A compression test shows very low numbers on all cylinders, the last lake runs have resulted in blow by, and a quick wet compression test has shown worn rings.
Sadly the shop that did the work has proven that they are not capable with other engines. They are the ones that caused the problems with the leaky headgasket surfaces which kept me out of the water during 2004. Unfortunatly this resulted in some rust rings and pitted cylinderwalls, which we elected to ignore to save this boating season. So all this really doesn't come as a surprise to me. Pistons are Sealed Power flat tops single eyebrow, Unfortunately I don't have any documentation as to what rings he selected. Certainly this is the last time that I have any work done by them, but more importantly I will never have one of my own engines built by someone else.
This is the part that really pisses me off more, as last year I built 15 BMW race engines and a few big buck restorations, and they are all perfect.

Matty, the water exits the risers on the down side where the flow combines with exhaust gasses. From here it is only 2 1/2' to the transom in a 3" SS pipe. The water flow used to cool the engine is really a trickle as water has such a huge capacity to dissipate heat / absorb energy.

Mario

[Ed Donnelly]

Check the amisivity your temp gun is set on. Very easy to get a 30 degree temp difference if it is not set for steel..Ed

[Ed Donnelly]

WHOOPS, Finger faster than brain tonight
Take the temp of your hot water coming out of your tap in your house. Then take the temp of the chrome spout. You will see a BIG difference....Ed

[John W]

You may want to get rid of the globe impeller, i put two brand new ones on my Hatteras, powered with Cummins diesels this past summer and both failed within 20 hours of Install. Also if yours waterpump has a keyed shaft the key can moveand cut a perfectly round hole in the waterpump cover.
Just a heads up.
JW