Engine Merc 888 (Ford 302) getting hot after warming up

Orion · 09-06-2016, 02:09 PM

Vapor lock is a carburetor issue not a cooling system issue.

AC2717 · 09-06-2016, 02:40 PM

I would say the thermostat is faulty even though new, cheap enough to replace and see what happens first. also check to see that the impellar in outdrive does not have and blockage from sucking things up, with the level of the lake could be a possibility

LakeErieFishing · 09-06-2016, 04:09 PM

Any chance the water circulating pump (front of engine) is faulty?

I will pull the thermostat to see if that removes the symptom. If so then the thermostat is faulty. I'll still probably drill a 1/8" hole in the flange. I've been told by enough career service managers that the lack of this could keep the water from circulating properly, even if the thermostat is working. I'll let you know what I find out....

Rich · 09-06-2016, 05:10 PM

Perhaps the pumps are worn out?

I've seen some pumps replaced by a mechanic lately, the pump body itself was all worn out because of sand and things that have been sucked up and run through the engine over time (such as spending a lot of time going to shallow water sand bars, or sucking up lake mud when the water is low).

So when you replace the raw water impeller, be sure to check the surfaces of the pump housing to see if there is excessive wear.

Also, if the pump bearings are wearing out, it could allow air to be sucked into the system and could cause a loss of cooling as water wasn't being efficiently sucked into the system.

8gv · 09-06-2016, 08:24 PM

Have you tried running it without the thermostat installed?

That might tell you if the trouble is elsewhere.

LakeErieFishing · 09-06-2016, 09:04 PM

I'm going to pull the thermostat and check it to make sure it opens and stays open at the correct temp. Also run the engine without it. If the engine stays cool without it I can narrow things down. If it doesn't the water circulating pump is what I suspect. Impeller in the out drive is new. The one I replaced looked new. No wear in the impeller housing. no gunk, sand or mud in the impeller area. I have other things to check. I'll let you know what find.

LakeErieFishing · 09-07-2016, 09:04 AM

I have not checked the water line between the gimbal housing and transom. Is that easy to check to see if it's crimped or damaged?

8gv · 09-07-2016, 09:28 AM

Is this an issue that has begun immediately after repair work?

If you had the outdrive off, it may help to remove it again and look for anything not quite right with the previous reassembly.

What brand/model/vintage outdrive is this?

HellRaZoR004 · 09-07-2016, 09:31 AM

Is the issue only at idle, or when you try to power up?

Have you tried starting the engine out of the water, with muffs? This should give you an idea of if water is passing through the engine. The added pressure from the hose may overcome the water pump so you can't rule that out....but if you're not seeing water drop from the gimbal housing then your engine isn't getting water and had a block somewhere. If it runs great and doesn't overheat, then I would suspect the water pump.

To check the water hose from the gimbal housing you need to pull the outdrive off.

What drive do you have?

LakeErieFishing · 09-07-2016, 10:05 AM

Quote:

Originally Posted by HellRaZoR004

Is the issue only at idle, or when you try to power up?

Have you tried starting the engine out of the water, with muffs? This should give you an idea of if water is passing through the engine. The added pressure from the hose may overcome the water pump so you can't rule that out....but if you're not seeing water drop from the gimbal housing then your engine isn't getting water and had a block somewhere. If it runs great and doesn't overheat, then I would suspect the water pump.

To check the water hose from the gimbal housing you need to pull the outdrive off.

What drive do you have?

I've had it on muffs. Water passes through the system and increasingly so as you push the RPMs up. Comes out through the two exhaust ports on either side of the outdrive (lower hull) and through the prop hub, with gusto. I've pulled the drive and a small trace of water was in the gimbal housing bellows but nothing that would indicate a backup or problem there.

I'm going to run the engine without the thermostat and see what happens.

HellRaZoR004 · 09-07-2016, 10:18 AM

Quote:

Originally Posted by LakeErieFishing

I've had it on muffs. Water passes through the system and increasingly so as you push the RPMs up. Comes out through the two exhaust ports on either side of the outdrive (lower hull) and through the prop hub, with gusto. I've pulled the drive and a small trace of water was in the gimbal housing bellows but nothing that would indicate a backup or problem there.

I'm going to run the engine without the thermostat and see what happens.

If you are not having issues (overtemp) while on the muffs then the thermostat is not the issue - unless you are not letting the engine run long enough to get up to temperature.

The gimbal housing bellows (I'm assuming you mean for the universal joint) should not have any water in it - and will not have anything to do with cooling the engine.

I would get a large trash bucket of water and start the engine with the drive submerged..make sure to leave the hose in the bucket. If you don't see water coming from the exhaust, inspect/replace the impeller.

LakeErieFishing · 09-07-2016, 01:05 PM

Quote:

Originally Posted by HellRaZoR004

If you are not having issues (overtemp) while on the muffs then the thermostat is not the issue - unless you are not letting the engine run long enough to get up to temperature.

The gimbal housing bellows (I'm assuming you mean for the universal joint) should not have any water in it - and will not have anything to do with cooling the engine.

I would get a large trash bucket of water and start the engine with the drive submerged..make sure to leave the hose in the bucket. If you don't see water coming from the exhaust, inspect/replace the impeller.

Lots of water comes out of the exhaust when drive has muffs on it. At low RPM water is still squirting out the edges of the muffs (using a hose with good water pressure and volume), but increase the RPMs and the seawater pump pulls every drop of water in and significantly more comes out of the exhaust and prop hub. If the boat is dropped into the lake and left on the trailer, same thing - you can feel the amount of water coming out of the exhaust.

LakeErieFishing · 09-18-2016, 05:28 PM

Quote:

Originally Posted by HellRaZoR004

If you are not having issues (overtemp) while on the muffs then the thermostat is not the issue - unless you are not letting the engine run long enough to get up to temperature.

The gimbal housing bellows (I'm assuming you mean for the universal joint) should not have any water in it - and will not have anything to do with cooling the engine.

I would get a large trash bucket of water and start the engine with the drive submerged..make sure to leave the hose in the bucket. If you don't see water coming from the exhaust, inspect/replace the impeller.

Okay, i did a compression check. The compression ranged from 105 to 120 on all cylinders except #2, which was only 75. I'm going to pull the head and see if it's okay or if I have a blown head gasket. The oil shows no signs of water getting in - it's very clear (not white). What do you think?

Dave R · 09-19-2016, 08:43 AM

Quote:

Originally Posted by LakeErieFishing

Okay, i did a compression check. The compression ranged from 105 to 120 on all cylinders except #2, which was only 75. I'm going to pull the head and see if it's okay or if I have a blown head gasket. The oil shows no signs of water getting in - it's very clear (not white). What do you think?

Could very well be a head gasket causing the low compression and the overheating. If there is a leak from the combustion chamber to the cooling system, the combustion gases in the water will keep the water from making full contact with the coolant passages in the cylinder head, right where it's needed most, and the head can get very hot which exacerbates the problem. If you have a bore scope, put it in the 75 PSI cylindeer and see if the piston top is nice and clean, if it is, you will know there's a coolant leak into that cylinder (that is steam cleaning the piston).

That said, squirt some oil in the cylinder with 75 psi and see if the compression test results improve If they do, it's likely not the head gasket.

105 to 120 on the other 7 cylinders is too low, IMO and the engine is tired. Now would be a great time to pull it and freshen it up a bit. With luck, you can just do a valve job, hone the cylinders, and put new rings and bearings in it. If the engine has a history of extended salt water use, it may make more sense to just replace the long block as the salt can make the coolant passages rather thin. Ford 302s are not exactly rare or expensive. A 351 Windsor would likely bolt right in too, but might require different ancillary bolt on parts since it has a taller deck height and different firing order than a 302 if memory serves.

ursa minor · 09-07-2016, 11:00 AM

Quote:

Originally Posted by LakeErieFishing

I have not checked the water line between the gimbal housing and transom. Is that easy to check to see if it's crimped or damaged?

It's been a while since I've messed with my drive personally but I do recall that hose as being prone to crimping. If you tilt the drive up to trailer position, I think you can see it from below but it's been a while. Also, mine is a first generation Alpha, yours pre-dates it. I like the ideas mentioned of running the boat out of the water on muffs and seeing if you're getting water out of the exhaust. You can also check the temperature of the hoses that inject water into the exhaust elbows vs. the engine side hoses to get some idea if the raw water is flowing.

LakeErieFishing · 09-07-2016, 01:07 PM

Quote:

Originally Posted by ursa minor

It's been a while since I've messed with my drive personally but I do recall that hose as being prone to crimping. If you tilt the drive up to trailer position, I think you can see it from below but it's been a while. Also, mine is a first generation Alpha, yours pre-dates it. I like the ideas mentioned of running the boat out of the water on muffs and seeing if you're getting water out of the exhaust. You can also check the temperature of the hoses that inject water into the exhaust elbows vs. the engine side hoses to get some idea if the raw water is flowing.

As far as checking water temp that goes into the elbows/manifolds, would you do that by touch of actual temp gauge?

HellRaZoR004 · 09-07-2016, 01:40 PM

So when exactly does the engine spike in temperature? What are you doing prior?

To read the exhaust manifold/riser/elbow temperatures I would use a simple IR heat thermometer. https://www.amazon.com/Raytek-MT4-No.../dp/B0002198GY (as an example)

LakeErieFishing · 09-07-2016, 02:28 PM

Quote:

Originally Posted by HellRaZoR004

So when exactly does the engine spike in temperature? What are you doing prior?

To read the exhaust manifold/riser/elbow temperatures I would use a simple IR heat thermometer. https://www.amazon.com/Raytek-MT4-No.../dp/B0002198GY (as an example)

I'll jump ahead - if they do show hot, what is the cause? The manifolds and risers aren't very old, not many hours (under 100), and only in fresh water. Would the water circulating pump on the front of the engine be faulty? I'll see what happens when I pull the thermostat as well.

As for the engine temp, I can be on the lake or on a hose and it shows hot after 5 to 10 minutes. It usually starts jumping up. It's not a slow climb. Its shows 1/4 into the green, then all at once jumps up into high green or into the red. On the hose is appears lots of water is being sucked through - a lot is coming out the exhaust and prop hub when the engine shows hot. The manifolds and risers are hot to touch, but that might be normal?

LakeErieFishing · 09-07-2016, 02:37 PM

Where is the engine temp sensor on the Merc 888 (Ford 302)? Could that be faulty?

HellRaZoR004 · 09-07-2016, 03:05 PM

Quote:

Originally Posted by LakeErieFishing

I'll jump ahead - if they do show hot, what is the cause? The manifolds and risers aren't very old, not many hours (under 100), and only in fresh water. Would the water circulating pump on the front of the engine be faulty? I'll see what happens when I pull the thermostat as well.

As for the engine temp, I can be on the lake or on a hose and it shows hot after 5 to 10 minutes. It usually starts jumping up. It's not a slow climb. Its shows 1/4 into the green, then all at once jumps up into high green or into the red. On the hose is appears lots of water is being sucked through - a lot is coming out the exhaust and prop hub when the engine shows hot. The manifolds and risers are hot to touch, but that might be normal?

How hot to the touch are we talking? Are you able to keep your hands on the elbows? If you can't then you're not getting enough water flow to cool the engine. The temp gauge is only green/red, i.e. no digits?

It's possible the sensor is bad, but if the manifolds/risers/elbows are to hot to touch then I doubt the sensor is the problem.

LakeErieFishing · 09-07-2016, 03:30 PM

The risers are pretty hot. Same for the manifolds. I wouldn't be able to put my hands on them and leave them there.

LakeErieFishing · 09-07-2016, 03:32 PM

Quote:

Originally Posted by HellRaZoR004

How hot to the touch are we talking? Are you able to keep your hands on the elbows? If you can't then you're not getting enough water flow to cool the engine. The temp gauge is only green/red, i.e. no digits?

It's possible the sensor is bad, but if the manifolds/risers/elbows are to hot to touch then I doubt the sensor is the problem.

They're pretty hot, you couldn't keep your hands on them for long. It's like water is getting sucked in pretty well at the seawater pump, but then not getting circulated to the manifolds and risers.

HellRaZoR004 · 09-07-2016, 03:46 PM

Closed cooled, or raw water cooled (i.e. do you have a heat exchanger and antifreeze)?

HellRaZoR004 · 09-07-2016, 03:52 PM

This was posted elsewhere and should give you some great idea on how to diagnose the issue.

http://forums.iboats.com/forum/engin...rheating/page2

Quote:

I have the same set up, only I converted mine to center risers. I still have the block off plate between the riser and the manifolds and the three hose style system as the original log style set up. I would do the following if you know that you have a good outdrive pump:While the engine is running at idle check the water flow through the system on both sides:From T-stat housing to the rear of manifold - if flow is bad, you have a restriction in the block, a bad circulating pump, or a restriction in the T-stat housing. If flow is good move on to the next check point.Flow from the manifold - disconnect the line from the front of the manifold. If flow is bad here you have a clogged manifold and it probably needs replacing or a good cleaning. If flow is good move on the next check point.Flow into the riser - disconnect the line feeding the riser. If flow is bad, you have a stuck closed thermostat or a restriction in the T-stat cover. If flow is good move to next check point.Idle relief ports - located on the side of the outdrive near the transom. If flow here is bad you either have a clogged riser or a stuck exhuast flapper. If flow is good you have to look at the engine internally.Do you have water in the cylinders, water in the oil? It seems as if you have checked all the above, so next I would do a compression check. Also, you might want to do a trick that helped me figure out what I think is my problem. I replaced all the water hoses on the cooling system with clear hose, for diagnositic use only. This way you can monitor flow at all points. I would check for air bubbles in the system. Also, make sure you put a clear hoses on the line coming from the outdrive water pump. If you have air, it could be a bad water pump seal, a loose hose connection on the suction side somewhere, or a leaking head gasket.I had air in my system, and pulled the heads. The gaskets were fine but my block was warped 0.018". The shop said they don't believe it was able to seal. Sorry for the long post, but I could talk for days about what I've done and I am down to the last straw.Hope this helps, good luck!! Keep us posted on your progress.

LakeErieFishing · 09-07-2016, 06:11 PM

Quote:

Originally Posted by HellRaZoR004

This was posted elsewhere and should give you some great idea on how to diagnose the issue.

http://forums.iboats.com/forum/engin...rheating/page2

If the water circulating pump is cause, how would I know this?

LakeErieFishing · 09-07-2016, 05:47 PM

Quote:

Originally Posted by HellRaZoR004

Closed cooled, or raw water cooled (i.e. do you have a heat exchanger and antifreeze)?

Raw water. Impeller/intake area is clean of any gunk Water tube from impeller housing looks good as well.

HellRaZoR004 · 09-07-2016, 06:24 PM

Quote:

Originally Posted by LakeErieFishing

Raw water. Impeller/intake area is clean of any gunk Water tube from impeller housing looks good as well.

Just some further clarification - do you have a split system? You could still have raw water cooling to a heat exchanger.

100% RAW Water Cooled

Split System

I would follow that path from inlet and make sure you are getting good flow.

LakeErieFishing · 09-07-2016, 09:05 PM

Quote:

Originally Posted by HellRaZoR004

Just some further clarification - do you have a split system? You could still have raw water cooling to a heat exchanger.

100% RAW Water Cooled

Split System

I would follow that path from inlet and make sure you are getting good flow.

The diagram was really helpful. Question - the two exhaust outlets on the lower back of the boat - if those are spitting a lot of water at idle, then more at 1,000 RPM and increasingly so as RPMs increase, wouldn't that indicate good water flow is traveling through the engine or the manifolds and risers, or all the above? How do I know if the engine is getting good water flow from the circulating pump?

Blue Thunder · 09-07-2016, 09:35 AM

Quote:

Originally Posted by Orion

Vapor lock is a carburetor issue not a cooling system issue.

Correct!!!!!

LakeErieFishing · 09-07-2016, 09:59 AM

Quote:

Originally Posted by Blue Thunder

Correct!!!!!

What I meant was steam created air pocket possibly forming that prevented the water from circulating properly through the thermostat. Vapor lock is carb, yep, but, well, you know what I mean....

09-06-2016, 02:09 PM	#1
Orion Senior Member Join Date: Feb 2003 Location: MA Posts: 914 Thanks: 602 Thanked 193 Times in 91 Posts	vapor lock? Vapor lock is a carburetor issue not a cooling system issue.

09-06-2016, 04:09 PM	#3
LakeErieFishing Member Join Date: Sep 2016 Posts: 42 Thanks: 10 Thanked 0 Times in 0 Posts	Engine heating up Any chance the water circulating pump (front of engine) is faulty? I will pull the thermostat to see if that removes the symptom. If so then the thermostat is faulty. I'll still probably drill a 1/8" hole in the flange. I've been told by enough career service managers that the lack of this could keep the water from circulating properly, even if the thermostat is working. I'll let you know what I find out....

09-06-2016, 05:10 PM	#4
Rich Senior Member Join Date: Jun 2012 Location: Derry / Gilford Posts: 1,247 Thanks: 74 Thanked 346 Times in 236 Posts	Perhaps the pumps are worn out? I've seen some pumps replaced by a mechanic lately, the pump body itself was all worn out because of sand and things that have been sucked up and run through the engine over time (such as spending a lot of time going to shallow water sand bars, or sucking up lake mud when the water is low). So when you replace the raw water impeller, be sure to check the surfaces of the pump housing to see if there is excessive wear. Also, if the pump bearings are wearing out, it could allow air to be sucked into the system and could cause a loss of cooling as water wasn't being efficiently sucked into the system. __________________ Don't listen to me, obviously I don't understand what I'm talking about! Let's help each other save time and money: WinniGas.com

09-06-2016, 09:04 PM	#6
LakeErieFishing Member Join Date: Sep 2016 Posts: 42 Thanks: 10 Thanked 0 Times in 0 Posts	Engine issues I'm going to pull the thermostat and check it to make sure it opens and stays open at the correct temp. Also run the engine without it. If the engine stays cool without it I can narrow things down. If it doesn't the water circulating pump is what I suspect. Impeller in the out drive is new. The one I replaced looked new. No wear in the impeller housing. no gunk, sand or mud in the impeller area. I have other things to check. I'll let you know what find.

09-07-2016, 09:04 AM	#7
LakeErieFishing Member Join Date: Sep 2016 Posts: 42 Thanks: 10 Thanked 0 Times in 0 Posts	Engine getting warm I have not checked the water line between the gimbal housing and transom. Is that easy to check to see if it's crimped or damaged?

The Following User Says Thank You to Orion For This Useful Post:
Blue Thunder (09-07-2016)

09-06-2016, 02:40 PM	#2
AC2717 Senior Member Join Date: Apr 2007 Location: Maynard, MA & Paugus Bay Posts: 2,585 Thanks: 756 Thanked 356 Times in 268 Posts	I would say the thermostat is faulty even though new, cheap enough to replace and see what happens first. also check to see that the impellar in outdrive does not have and blockage from sucking things up, with the level of the lake could be a possibility __________________ Capt. of the "No Worries"

09-06-2016, 08:24 PM	#5
8gv Senior Member Join Date: Jan 2012 Posts: 2,121 Thanks: 64 Thanked 751 Times in 485 Posts	Have you tried running it without the thermostat installed? That might tell you if the trouble is elsewhere.

09-07-2016, 09:28 AM	#8
8gv Senior Member Join Date: Jan 2012 Posts: 2,121 Thanks: 64 Thanked 751 Times in 485 Posts	Is this an issue that has begun immediately after repair work? If you had the outdrive off, it may help to remove it again and look for anything not quite right with the previous reassembly. What brand/model/vintage outdrive is this?

09-07-2016, 09:31 AM	#9
HellRaZoR004 Senior Member Join Date: May 2012 Location: Litchfield/Gilford Posts: 828 Thanks: 233 Thanked 224 Times in 131 Posts	Is the issue only at idle, or when you try to power up? Have you tried starting the engine out of the water, with muffs? This should give you an idea of if water is passing through the engine. The added pressure from the hose may overcome the water pump so you can't rule that out....but if you're not seeing water drop from the gimbal housing then your engine isn't getting water and had a block somewhere. If it runs great and doesn't overheat, then I would suspect the water pump. To check the water hose from the gimbal housing you need to pull the outdrive off. What drive do you have?

09-07-2016, 01:40 PM	#17
HellRaZoR004 Senior Member Join Date: May 2012 Location: Litchfield/Gilford Posts: 828 Thanks: 233 Thanked 224 Times in 131 Posts	So when exactly does the engine spike in temperature? What are you doing prior? To read the exhaust manifold/riser/elbow temperatures I would use a simple IR heat thermometer. https://www.amazon.com/Raytek-MT4-No.../dp/B0002198GY (as an example)

09-07-2016, 02:37 PM	#19
LakeErieFishing Member Join Date: Sep 2016 Posts: 42 Thanks: 10 Thanked 0 Times in 0 Posts	Where is the engine temp sensor on the Merc 888 (Ford 302)? Could that be faulty?

09-07-2016, 03:30 PM	#21
LakeErieFishing Member Join Date: Sep 2016 Posts: 42 Thanks: 10 Thanked 0 Times in 0 Posts	The risers are pretty hot. Same for the manifolds. I wouldn't be able to put my hands on them and leave them there.

09-07-2016, 03:46 PM	#23
HellRaZoR004 Senior Member Join Date: May 2012 Location: Litchfield/Gilford Posts: 828 Thanks: 233 Thanked 224 Times in 131 Posts	Closed cooled, or raw water cooled (i.e. do you have a heat exchanger and antifreeze)?