98 OMC fuel injected 5.7 overheating

stang32

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Jul 16, 2004
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as stated, the engine temp climbs above 170 @ idle but not much higher, when you take it out & run it, the temp is steady @ 185ish. when you idle down, the temp spikes over 200, closed to 230.
the boat has new impeller, thermostat & manifolds/risers.
any thoughts
 

HT32BSX115

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when you idle down, the temp spikes over 200, closed to 230.
the boat has new impeller, thermostat & manifolds/risers.
any thoughts
Howdy,

Yeah. You have cooling water flow restriction someplace between the raw water pump and the engine, or the impeller is bad (regardless of how new it is) also, How "BAD" was the previous impeller(s) and did you locate and clear any debris from previous impeller failures? (like plugged oil cooler/PS-cooler etc?)

Regards,


Rick
 

Scott Danforth

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Agreed, either a flow issue into the motor, thru the motor, or exiting the motor
 

stang32

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the impeller was changed for maintenance, not due to failure, no debri/damage found. the RWP runs off of the belt/pulley set up similar to the bravo set up but smaller,.
the RWP hose runs to the thermostat housing , which was also addressed & nothing found there.. the hoses all look in great condition, the boat has only been used on lake but it does have over 800 hrs on the motor.
any ideas on how to run down a blockage?

also, when first diagnosing the o/h the IR temp gun read 20 degrees hotter on the starboard riser than the port riser
 
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Scott Danforth

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Check the raw water flow. Should be over 20 gpm at 1500 rpm or above. (5 gallons in 15 seconds) If you have a power steering cooler, generally that is the first cooler that gets plugged. That are generally on the intake side of a belt driven raw water pump
 

HT32BSX115

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.............the hoses all look in great condition, .........
.......any ideas on how to run down a blockage?...........

..............also, when first diagnosing the o/h the IR temp gun read 20 degrees hotter on the starboard riser than the port riser

Yes. The first thing to do is to ensure that you have adequate flow from the pump.

That will rule out blockage of the water pickup and hoses to the raw water inlet.(hoses can "look great" but be blocked internally.....

It's possible for risers to run hotter on one side over the other if the flow is low. The one that is cooler is getting more flow than the other side.
 

stang32

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the engine is RWC, no water heater, we have reduced speeds fast,chopped, & gradual with the same results.

today I put together all the parts listed on the overheat diagnostic pdf, only to get to the boat & find out all the hose sizes listed were wrong. the RWP on the boat runs off of a pulley, & not off of the crank as pictured in the PDF. so, anyway, I ran a bypass hose from the RWP intake over the side of the boat & directly into the lake with the same results.
i pulled the water outlet hose & ran the boat @ 1500 RPM to find that i am only pumping 3.25 gallons in 15 seconds,
I pulled the RWP to inspect, the impeller looks ok/new, the plate & cam look to have been re-used,
i pulled the thermostat & it does not look as new as I was lead to believe. i took it home & tossed it in a pot of boiling water, the therm started to open around 165 & didnt fully open until 175-180.
I would love to get a new RWP kit with the plate, change the thermostat & run the diagnostic test with the correct equipment once they are in.
my friend has layed out a lot of money on this boat & I need to be absolutely sure what I am suggesting is necessary.
thank you everyone for all your input, please keep it coming
 

HT32BSX115

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I have a Mercruiser Bravo. The impeller is pretty "robust" ........ Having said that, I have never tried a flow test with one but I do know that low flow WILL cause overheats that are directly proportional to the amount of available flow, at a constant power setting. AND, if the flow is low enough, there will be an overheat at some higher power power setting where the flow is not enough to handle the higher power output.

It's just simple thermodynamics.

You didn't indicate what model you have. If the boat is a 1998 year model, the engine and drive package could be one of the following:
572BPBYC 1998
57FCPBYC 1998
57FCPBYD 1998

572BPLKD 1997
572BPLKR 1997
574BPLKD 1997
57FAPLKD 1997
57FCPLKD 1997
57FDPLKD 1997

Looking at the parts breakdown for the above models @ http://epc.brp.com/ it appears that the pump is the same for all models (I didn't check all the part numbers) I suppose you also know the engine and drive you have is a Volvo SX so part numbers can be cross referenced to Volvo Penta.

Also, if there's a smaller pump that could be used on that engine, it's possible that someone installed the wrong pump. But, understand that the correct pump for that engine uses a #3856039 impeller. That impeller and pump housing etc is used in ALL the engines (from 3.0L to 8.2L ) It's MORE than adequate to flow enough water for a big-block!

So if there isn't enough flow, it's likely due to a restriction someplace in the circuit.

Also, your raw water pickup (either thru hull[if installed] or drive pickup) might be plugged with debris/corrosion/Zebra mussels etc)

If you suspect blockage in the pick-up or hoses from it, try connecting a larger hose directly to the raw water pump and throw it over the side into the lake and see if the pump output is better. If it is, the hose(s) and/or pickup is/are plugged someplace.

Cheers,


Rick
 

stang32

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I have a Mercruiser Bravo. The impeller is pretty "robust" ........ Having said that, I have never tried a flow test with one but I do know that low flow WILL cause overheats that are directly proportional to the amount of available flow, at a constant power setting. AND, if the flow is low enough, there will be an overheat at some higher power power setting where the flow is not enough to handle the higher power output.

It's just simple thermodynamics.

You didn't indicate what model you have. If the boat is a 1998 year model, the engine and drive package could be one of the following:
572BPBYC 1998
57FCPBYC 1998
57FCPBYD 1998

572BPLKD 1997
572BPLKR 1997
574BPLKD 1997
57FAPLKD 1997
57FCPLKD 1997
57FDPLKD 1997

Looking at the parts breakdown for the above models @ http://epc.brp.com/ it appears that the pump is the same for all models (I didn't check all the part numbers) I suppose you also know the engine and drive you have is a Volvo SX so part numbers can be cross referenced to Volvo Penta.

Also, if there's a smaller pump that could be used on that engine, it's possible that someone installed the wrong pump. But, understand that the correct pump for that engine uses a #3856039 impeller. That impeller and pump housing etc is used in ALL the engines (from 3.0L to 8.2L ) It's MORE than adequate to flow enough water for a big-block!

So if there isn't enough flow, it's likely due to a restriction someplace in the circuit.

Also, your raw water pickup (either thru hull[if installed] or drive pickup) might be plugged with debris/corrosion/Zebra mussels etc)

If you suspect blockage in the pick-up or hoses from it, try connecting a larger hose directly to the raw water pump and throw it over the side into the lake and see if the pump output is better. If it is, the hose(s) and/or pickup is/are plugged someplace.

Cheers,


Rick


rick, i have seen this pump on other volvo/omc's so i am sure it is ok. since i did not have the correct hoses yesterday I will be going back armed with the correct ones tomorrow. i will get another hose that actually fits the pump & bypass the drive & p/s cooler. when i did it yesterday I saw a lot of air bubbles going into the pump, but that was probably because the hose was too big & I crushed it to achieve fitment.,
the boat has never been in salt water, always a lake, so if anything it is blocked by seaweed. I am thinking about putting the thermostat housing back in place without the thermostat to see if the issue is still there,.
 

HT32BSX115

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when i did it yesterday I saw a lot of air bubbles going into the pump, but that was probably because the hose was too big & I crushed it to achieve fitment.,
If you're seeing air bubbles, you have a leak in the inlet either from where you crushed the end of the hose or someplace else.



Seal that suction-side leak and you will likely solve your overheating problem!

//
 

stang32

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today I put the pump & thermostat housing back on the boat & ran it without a t stat, the engine did not get hot at all, would not go over 120. tomorrow I will be installing a new t stat & see where that takes us.
my friend says the previous mechanic who "replaced" the t stat told him the old one had a chunk of impeller stuck in it. but the boat only has 8 hrs on it since this t stat was "replaced" & it looks like its been there for years. im just sayin......
 

stang32

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Messages
513
i installed the thermostat & although it seems to run a bit cooler, is still climbs pretty high. now as f that wasn't enough, now the boat has a constant stalling problem, which was there prior but not as constant as it is now, now it is not running more than is is running. i have checked the fuel pumps & i am not sure i am getting enough fuel pressure. the spreader valve on the fuel line is reading 14psi, the schreader on the rear fuel pump assy is ony 10 psi, i have read that i should have 29psi . the boat has throttle body injection. i have read about the black paint chips in the screens but i believe that is on the newer EFI models, can anyone confirm?
also which pump is which, high presusre & low?
one pump is above the water seperator & 1 is in the back of the motor on top of some sort of box, also were the shredder valve is.
does this engine have a pressure regulator?
where are the screens located that get clogged?
the rear pump got brutally hot at 1 point but cooled down shortly after. the IR gnu read over 150 degrees.
 

HT32BSX115

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i installed the thermostat & although it seems to run a bit cooler, is still climbs pretty high. now as f that wasn't enough, now the boat has a constant stalling problem, which was there prior but not as constant as it is now, now it is not running more than is is running. i have checked the fuel pumps & i am not sure i am getting enough fuel pressure. the spreader valve on the fuel line is reading 14psi, the schreader on the rear fuel pump assy is ony 10 psi, i have read that i should have 29psi . the boat has throttle body injection. i have read about the black paint chips in the screens but i believe that is on the newer EFI models, can anyone confirm?
also which pump is which, high presusre & low?
one pump is above the water seperator & 1 is in the back of the motor on top of some sort of box, also were the shredder valve is.
does this engine have a pressure regulator?
where are the screens located that get clogged?
the rear pump got brutally hot at 1 point but cooled down shortly after. the IR gnu read over 150 degrees.

I am not familiar at all with any vintage OMC/Volvo EFI engine but you do have a fuel pickup in the tank with a screen on it, an anti-siphon check valve at the tank and a fuel vent. Any of them could be plugged.

As far as the rest of it, if you don't have an OEM service manual, (OMC or Volvo Penta) now might be a good time to obtain one.
The online one might help, but it does have errors and mis-information in it.

I am not sure I would trust if for complicated EFI info. http://boatinfo.no/lib/omc/manuals/1986-1998omcmanual.html#/0
 

MasterGoa

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Jul 15, 2012
Messages
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The high pressure pump is in the back of the engine, near the fuel cooler.
The low pressure pump usually at the same place as the fuel separator filter.

If it is anything like my Ford EFi's, the high pressure makes 29PSI at idle and has to go up to 39PSI
at WOT. You can check this by gunning the throttle while the fuel pressure gauge is attached.
In my case, I had WOT issues which were because the HP fuel pump was going bad.
Gunning the throttle actually displayed lower pressure (20PSI).

If it were you low pressure pump, the engine would work normally but experience long cuts at high RPM.
The low pressure pump provides only 3PSI as per spec...

Haven had cold temperature issues with my engines, I cannot help you with your hot ones,
however I do see temps go higher when getting off plane to idle for a good 20-30 seconds...
So this might be normal...
 
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