Engine overheating

[ConchPirate]

Engine - Port: 5.0GXi-E Model # 3869255/Serial # 4012105456/566 hours.

After first run with new to us boat, the port engine seawater pump began leaking out the bearing seal, but temp was fine and steady at 175 (and impeller was in great shape). Replaced the pump with a new unit and it seemed to be OK dockside. Next run while idling out the canal and with temp running at 175 for about 3 minutes it started climbing to 200. Put it in neutral and increased rpms and it began dropping, finally settling on 175. Once on the water ran up on plane, did a few minutes of WOT, back to 3Krpm, and temp stayed at 175 for entire remainder of the trip. Next trip -- same exact issue! 3rd trip -- same scenario. So today, I pulled the thermostat housing, boiled and cleaned it, installed a new 150° thermostat, put it all together and cranked it up dockside. Guess what -- SAME exact issue just sitting at dock! It gets to 175, holds for a minute, then heads to 200. Increase rpms for 15 seconds and it drops right back down and just stays at 175.

Welcome ideas as to what to check next. BTW - manifolds and risers were replaced in MAR 2019 by PO.

TIA/ Dave

 

[alldodge]

I'm assuming this is open cooled motor?

Get a piece of clear hose, a barbed fitting and hose clamps from the hardware store. Remove the hose coming from the pump to the thermostat housing, and place clear hose inline with and connect to housing.

Your looking for bubbles while running in the water (not on a hose)

 

[ConchPirate]

I'm assuming this is open cooled motor?

Yes it is raw water cooled

Your looking for bubbles while running in the water (not on a hose)

OK. Yes, kept on a lift and sits in water for testing.

Not sure how it would be getting air, but will let you know. Thanks.

 

[Scott Danforth]

Look at the fitting on the drives. If its corroded, you will suck air on plane

 

[ConchPirate]

Look at the fitting on the drives. If its corroded, you will suck air on plane

It isn't on plane when this is happening. Either just sitting at the dock or moving at idle speed after initial startup for the day. Keeping/putting it in neutral and increasing rpms seems to bring temp back down, and then it doesnt go back up.

Not sure which fitting on the drive you were referring to, but suspect you mean where the water hose connects from the outdrive to the transom plate? Outdrive is an SX-M model.

Also not sure how air would be in the system (per Alldodge) if I don't see water leaking. Wouldn't I see water leaking at a hose joint when engine is off? Or does the pump generate air?

 

[alldodge]

Air would come from a leak before the pump (suction side) or a restriction (corrosion)

 

[ConchPirate]

So clear tube test didn't show any air bubbles. Problem did it again when we went out on the 4th. While heading to the harbor it went to 200 and alarmed. I shut the engine down and finished getting to the harbor on just the strbd engine. Once past the no wake zone, fired the port engine up, noticed the temp was about 190 on the gauge. Pushed both throttles to get on plane, then ran for 20 minutes at 3000 rpm. The port engine temp dropped to 175 and stayed there without ever going beyond the 175 mark. Anchored up for a couple hours. Started the engines up to cruise and ran for an hour at various rpms from 1800 to 3500. Temp never went above the 175 mark. Finally headed for dock and the rest of the trip - at all speeds/rpms, temps stayed at 175 without fail. Very perplexing. Any other ideas? If there were blockage I should think it would have been apparent during and just after sea trials or with the leaky pump on it when it was tested and first trip. It never did do it then, only after the new pump replacement. Do the sea water pumps come bad out of the box?

 

[alldodge]

Don't know, either restricted flow or pump issue

Have not heard of a bad pump out of the box, and with no bubbles then unable to think about head gasket. Puzzler is was over heating then that issue went away like if an air pocket was purged out from the motor

 

[ConchPirate]

Following up with findings. Bad pump out of the box!! Knew there was no overheating issue before replacing the pump and pump was only replaced because the original pump began throwing water out the bearing. So the issue had to be related to the new pump and or my work. While I am not perfect in any way, I just didn't see anything I could have done incorrectly. I had bought a re-build kit to rebuild the original pump but turned out the pulley bearing shaft wasn't useable due to excessive corrosion so I decided I would pull the new pump housing off to check the impeller to be sure it hadn't come apart prematurely (I had lubed it with Dawn prior to installation to ensure that wouldn't happen). And then - VOILA - the issue became apparent immediately (or at least I was hoping). The O-Ring was all "smushed". Yep, some factory assembly person had put it together incorrectly. So, I put some lube on a new O-Ring, carefully reinstalled the housing and then tested the engine at idle. Ran for over twenty minutes and never got above the 160/165 mark on the gauge (it would get to 200 in about 8 minutes before). SUCCESS. Cooling all better now. Lesson learned (again) - never believe a new part has to be good.

O-Ring/Gasket I pulled from new pump pictured.

 

[Scott Danforth]

thanks for coming back to bring closure to the thread.

 

[ConchPirate]

UPDATE #2 --

Well, I was wrong!! The bad O-Ring did not resolve the issue. Being as how I didn't have my IR gun at the boat last time and mistakenly had left the hose shut off valve ON, the engine didn't overheat according to the dash gauge. However next day it did due to not using a hose hookup. And with the IR gun that day I noticed that the manifold and risers were getting upwards of 180-190 before the thermostat even opened (about 120 at the thermostat housing). SOoooooo....

Today I hooked up a couple lengths of clear tubing to the starboard engine raw water suction hose from the starboard outdrive straight to the port engine RW pump input (see pic). I primed the line from the hose input line and left it run until the engine started then shut the fresh water off so it was pulling from just the starboard outdrive. Lo and behold, after about 20 minutes of sitting and idling the manifolds and risers never got above 120F. That was just before the thermostat opened because after they were running around 111-115F. PERFECT.

So I then disconnected the temporary line, and put the clear line at the pump input (I had done output last time). Although I primed it from the hose and it seemed OK at first, it soon appeared to be getting some air and the manifold/riser temps went up to the 180 mark rather quickly.

So, there is a suction side issue. Now I am wondering if anyone knows if there is a power steering oil cooler on the port side engine being that the port power steering pump is just running in a loop? That could be blocked but cant see one and don't know where it would be located if it is there.

Engine - 5.0GXi-E Model # 3869255/Serial # 4012105456
Transom Assembly – Port: TSK SX-M Model # 3868844/Serial # 4151040976
Outdrive Serial Port: SX-M (Gear Ratio 1.6) Model3868891 Serial # 4202090193

So new question -

How to check and narrow down the feed problem from this point? Getting to the back of the engine is near impossible without pulling out batteries/HWH/trim pumps (both systems)/trim tabs pump and maybe having to cut a hole in the transom deck! Is it possible that the passage gets blocked up in the lower unit? Boat sits on a lift so I could pull those plastic inlet parts perhaps, but don't know if it is going to provide any good data or worth the time. Can it be back-flushed, and if so, how? Ideas???? TIA

Link to video:

https://youtu.be/JKSvi37ojN0

 

[alldodge]

The O-Ring was all "smushed". Yep, some factory assembly person had put it together incorrectly.

Just dawned on me, you installed a new pump, but it sounds like the pump cam with the impeller already installed. Is this correct?

If it was already installed, then the impeller could have created a set and really needs to be replaced

Watching the vid, the motor was running for 15 seconds before water came into the pump (when you said this is with water on). That 15 seconds can damage the impeller

 

[ConchPirate]

Just dawned on me, you installed a new pump, but it sounds like the pump cam with the impeller already installed. Is this correct?

Yes. The new pump was a VP complete unit right out of the box. The O-Ring had been pinched at factory but was not causing any issue.

If it was already installed, then the impeller could have created a set and really needs to be replaced

The impeller is still soft and pliable and looked like any new item when inspected during the O-Ring replacement. I was able to slowly rotate it (with some dawn lube) to ensure all vanes were always touching. As mentioned when I connected the starboard engine water intake line to the port engine pump input the port engine ran within all temp specs right from the git go. Let it idle for about 30 minutes total dockside and manifolds never got above 120F. Most of the time they were showing about 112-115F on the IR gun. The canal water temp was about 93F at the pump.

Watching the vid, the motor was running for 15 seconds before water came into the pump (when you said this is with water on). That 15 seconds can damage the impeller

I should clarify my comment there. After connecting the small clear tubing, and PRIOR to starting the engine I connected the water hose to the VP installed fresh water hose flush port. I had the hose fresh water running and filling the pump/block prior to and just after starting the engine. I wouldn't start it knowingly without there being water at the pump so it does not affect the impeller. It took me about 10 seconds to get back to the compartment and the camera back on, but during that time it was running with pressurized water from the hose. After I got the camera back on, and I said it was with the water on, what I meant was that I had turned the hose water off where the hose attaches to the flush port, and it was then running on the outdrive leg supply canal water only.

After that video I posted, I re-did the long line to the starboard engine normal water intake line and again the temps stabilized and it ran just as the factory specifies it should, so I have to believe the impeller is A-OK and the supply line from the leg to the pump input is either partially clogged or somehow is getting air.

I also found that the port engine is connected as a "slave", and the power steering lines from the port pump simply tie back to each other via a brass union so there is no oil cooler in the water intake circuit for the port engine.

I'm thinking something may have gotten sucked into the outdrive water passage on the lower unit, but don't know if there is any screening in there that can be checked, I want to try to get some video of the water line from the pump back to the TP to see if it is one piece or there may be a union that needs a clamp tightened.

Sorry for not writing it up better yesterday.

I'm now looking for a good schematic/diagram of how the water gets from the lower unit to the hose in the Transom Plate to determine if there is some way of testing for blockage.

Thanks again for your time

 

[ConchPirate]

Just dawned on me, you installed a new pump, but it sounds like the pump cam with the impeller already installed. Is this correct?

If it was already installed, then the impeller could have created a set and really needs to be replaced

Watching the vid, the motor was running for 15 seconds before water came into the pump (when you said this is with water on). That 15 seconds can damage the impeller[/QUOTE

 

[Scott Danforth]

all VP motors have a PS cooler regardless if its a single or double install. its what holds the hose to the transom shield.

also, if you are getting bubbles, look at the hose connection on the drive. the early ones were crap metal and they would corrode in 3 years in fresh water, and about 1.5 years in salt water.

later ones were plastic and prone to cracking after 2-3 years.

 

[ConchPirate]

Thank you Scott. I'll raise the OD up and see what I can see of the hose located there.

 

[ConchPirate]

all VP motors have a PS cooler regardless if its a single or double install. its what holds the hose to the transom shield.

also, if you are getting bubbles, look at the hose connection on the drive. the early ones were crap metal and they would corrode in 3 years in fresh water, and about 1.5 years in salt water.

later ones were plastic and prone to cracking after 2-3 years.

Scott - were you referring to one of the hose connections in the following diagrams? If so which one??

 

[Horigan]

The short horizontal piece at the bottom of the second photo next to O-ring 10 is plastic and can break and introduce air. It’s held on by a large plastic nut that is accessible when you pull the drive. When you tilt the drive all the way up you will be able to see the rubber hose that goes to it on the front side. The hose should be firmly attached to the tilted portion of the drive via this plastic section.

 

[saf]

I have the same outdrive, had an air leak problem last year. In my case it turned out to be burnt rubber boot and the copper pipe that goes through it (circled with orange on the lower unit diagram). I had an exhaust overheat resulting from a defect in newly installed riser. Apparently, overheated exhaust gases burnt (shrunk) the rubber boot and burnt a small hole in the copper pipe that goes through it. Even though this pipe is well below the water line, it was sucking in exhaust gases that go by.
The plastic nipple in the upper unit (circled with blue) is normally below the water line and should not result in air leak unless on the plane (gasket #8 also could be a culprit in this case). So, if it is not the lower unit leak, like in my case, it might be the through-transom connecting pipe (circled with orange).

 

[Scott Danforth]

Scott - were you referring to one of the hose connections in the following diagrams? If so which one??

2nd photo, the plastic connection on the back side of the gimble