120 Diesel Lehman Over heating

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T

Tom Foolery

Member
Joined
May 29, 2016
Messages
19
Location
USA
Vessel Name
Miller Time
Vessel Make
36' Grand Banks
May I ask all of you experienced and knowledgeable folks to take a look at my video of my motor running and the Coolant reservoir "Burping" and comment if this is "Normal"
And if it isn't I'd, sure be grateful for any constructive comments and suggestions as to where I can find the culprit......
:banghead:
Thanks

Tom McBride
Long Beach
Shoreline Marina.


https://drive.google.com/drive/folders/1FRLH4lPt2l-U2LKLyUI27h_mAYHtEXci?usp=sharing
 
Last edited by a moderator:
I suspect I have a compromised Head Gasket .
 
I could not see the video since it wants me to sign in. But I would call Brian at American Diesel. He is the man as far as Lehmans go. 804-435-3107
 
you should set the Drive for no request needed as some may not click on it.
I do not see any overheat issue from that, with rad cap off that is what they all do. Burping air suggests you need to bleed it.
1st video at 48 second mark your left hand is beside the petcock. With engine off have you bled the air out of there? open it and let out air until only water comes out.

Your temp gauge was around 120, it is not up to operating temp until about 170-180.
Rad caps. If you are loosing water after operation, replace caps.
There may be more to it, but reply to this first.
 
Last edited:
Sorry folks,
I just realized my error and have OPENED sharing!
Thank you ALL for your assistance
TM
 
Thank you for your reply,
Answers and comments below

Soo-Valley said:
you should set the Drive for no request needed as some may not click on it.
DONE Thank you for the suggestion

I do not see any overheat issue from that, with rad cap off that is what they all do. Burping air suggests you need to bleed it.
OK, I thought I bled it correctly,
I left the air nipple on the Exhaust Manifold open and filled the reservoir until it "peed out, then closed it and then started the motor

1st video at 48 second mark your left hand is beside the petcock. With engine off have you bled the air out of there? open it and let out air until only water comes out.YES I have done this procedure

Your temp gauge was around 120, it is not up to operating temp until about 170-180.
OK, good to know, I may have been "hasty. I'll attempt run the motor again and get it up to operating temp

Rad caps. If you are loosing water after operation, replace caps.
Noted

There may be more to it, but reply to this first.
Click to expand...
 
Comodave said:
I could not see the video since it wants me to sign in. But I would call Brian at American Diesel. He is the man as far as Lehmans go. 804-435-3107
Click to expand...

Thank you...NOTED
 
Tom,
Do the bleed again and fill the reservoir, rad cap on and run up to operating temp. If possible do a short run at cruise, return, let it cool and see if you lost any fluid.
As suggested a head gasket issue would do more than a few burps. as it heats there will be water expansion which is seen as it overflows.
As you can see I am hoping it is not head gasket.
 
Soo-Valley said:
Tom,
Do the bleed again and fill the reservoir, rad cap on and run up to operating temp. If possible do a short run at cruise, return, let it cool and see if you lost any fluid.
As suggested a head gasket issue would do more than a few burps. as it heats there will be water expansion which is seen as it overflows.
As you can see I am hoping it is not head gasket.
Click to expand...
This is a GREAT suggestion, I wonder if I've been too hasty thinking that there is a Head gasket compromise, I WILL do as you have suggested and ensure that there is NO AIR remaining in the system before "jumping to conclusions"
Additionally, I appreciate your concern and hopes that it is not a HG Issue :thumb:
 
hobbystuff said:
Did the engine actually overheat?
Click to expand...
So, This is good question and Yes,
It did on two different occasions.

I warmed the motors as usual for about half an hour before going underway, leaving the marina operating temps approx. 120f, (Normal)
then while underway (idling) after leaving the marina and bumping up the RPM easily outside of the no wake zone (never aggressively or excessively,
the Overheating alarm sounded and the temp gauge showed 220f (ish)

I immediately shut it down and left the other motor running to get me back to my dock,

I went below and my catch basin was FULL of Coolant and Water and the Reservoir was empty.
 
Tom Foolery said:
So, This is good question and Yes,
It did on two different occasions.

I warmed the motors as usual for about half an hour before going underway, leaving the marina operating temps approx. 120f, (Normal)
then while underway (idling) after leaving the marina and bumping up the RPM easily outside of the no wake zone (never aggressively or excessively,
the Overheating alarm sounded and the temp gauge showed 220f (ish)

I immediately shut it down and left the other motor running to get me back to my dock,

I went below and my catch basin was FULL of Coolant and Water and the Reservoir was empty.
Click to expand...
This last bit changes it up a bit. If it overheats away from dock shut down, you can always restart to dock.
Other things can be raw water impeller, heat exchanger, hoses, thru hull. Still not seeing the head gasket looking at video.
 
Additionally,

I have inspected ALL hoses and looked for any collapsing hoses, inspecting for integrity, cracks, leaks, rips or tears.

I have removed just about every cooling hose looking for any obstructions or anything that would restrict water coolant/flow.

Cleaned out ALL coolers (Oil and Transmission)
Took a brass gun cleaner and cleaned ALL small holes removing any (calcium?)
Build-up.

Removed flushed, cleaned and reinstalled my Coolant Reservoir.

Removed and tested my thermostat testing it to boiling water and watched it operate and open as it heated up to temp. (Worked perfectly) drain hole in thermo clean and clear - reinstalled.

Removed Front Exhaust Manifold cover (replaced gasket) and Rear manifold cover (replaced gasket) and inspected and cleaned Exhaust Elbow as well as the salt water elbow (gasket replaced)
No obstructions in the Exhaust manifold and was bale to see adequate light all the way thru.

Re-assured by my bottom cleaner that the strainer has no obstructions where the water coms into feed the Jabsco impellers.
Checked and removed that hose inspected.

Removed and replaced my rubber Jabsco impeller.
 
Answer in red typing:

Soo-Valley said:
This last bit changes it up a bit. If it overheats away from dock shut down, you can always restart to dock.
Yes, I did restart it to assist me in docking it as I have yet to try to dock my vessel with only one motor.
I know it can be done and I should practice more but your comment is noted, thank you.

Other things can be raw water impeller, heat exchanger, hoses, thru hull. Still not seeing the head gasket looking at video.
Yes, please see my post just above I just adressed these items. Thank you
Click to expand...
 
Tom Foolery said:
So, This is good question and Yes,
It did on two different occasions.

I warmed the motors as usual for about half an hour before going underway, leaving the marina operating temps approx. 120f, (Normal)
then while underway (idling) after leaving the marina and bumping up the RPM easily outside of the no wake zone (never aggressively or excessively,
the Overheating alarm sounded and the temp gauge showed 220f (ish)

I immediately shut it down and left the other motor running to get me back to my dock,

I went below and my catch basin was FULL of Coolant and Water and the Reservoir was empty.
Click to expand...

So here is my view.

(a) Perhaps some good news - I listened to the video you posted and the engine sounded pretty normal even after overheating. I experienced a scored #6 cylinder after a mild overheat following work from a local mechanic. We ended up with piston slap that was quite obvious - I didn't hear that on your video, so hopefully that is good news.

(b) If the engine overheated and pushed coolant out I suspect you need to do the fill/bleed cycle a few times to get all the air out as was suggested above.

Bottom line though - you need to look in to why the engine overheated - start with the raw water system and look at the heat exchanger for sure.
 
hobbystuff said:
So here is my view.

(a) Perhaps some good news - I listened to the video you posted and the engine sounded pretty normal even after overheating. I experienced a scored #6 cylinder after a mild overheat following work from a local mechanic. We ended up with piston slap that was quite obvious - I didn't hear that on your video, so hopefully that is good news.

(b) If the engine overheated and pushed coolant out I suspect you need to do the fill/bleed cycle a few times to get all the air out as was suggested above.

Bottom line though - you need to look in to why the engine overheated - start with the raw water system and look at the heat exchanger for sure.
Click to expand...

:thumb: That is what I saw and heard. Tom is ready to do a test run under load after another air bleed and fill. Again watch those rad caps, mine were replaced when I could not find any reason for water loss and now no water loss. They are only 4lb rad caps
 
Soo-Valley said:
:thumb: That is what I saw and heard. Tom is ready to do a test run under load after another air bleed and fill. Again watch those rad caps, mine were replaced when I could not find any reason for water loss and now no water loss. They are only 4lb rad caps
Click to expand...
Thanks, I'll give it GO and Let Ya'll know.
 
Reply in red below:

hobbystuff said:
So here is my view.

(a) Perhaps some good news - I listened to the video you posted and the engine sounded pretty normal even after overheating. I experienced a scored #6 cylinder after a mild overheat following work from a local mechanic. We ended up with piston slap that was quite obvious - I didn't hear that on your video, so hopefully that is good news.I'd say THIS is good news yes.

(b) If the engine overheated and pushed coolant out I suspect you need to do the fill/bleed cycle a few times to get all the air out as was suggested above.
Noted and thanks!

Bottom line though - you need to look in to why the engine overheated - start with the raw water system and look at the heat exchanger for sure.
Noted and will do. Thanks
Click to expand...
 
I have had a head gasket leak for probably around 1000 hours, maybe more than 3700 hours.

After explaining a possible head gasket leak diagnosed by me and experts I had talked to,, another Lehman experienced pro diagnosed it by using a coolant system pressure checker. He would let the pressure build, release it, watch it, bleed, let it build, bleed. After several times he was confident it was a head gasket as I had also told him I removed and pressure checked the manifold.

It could be a couple other things like a cracked block or pinhole in a cylinder....but not likely.

I also get a tiny bit of oily soot or oil in the coolant that suggests head gasket too.

Pros said if no issues other than bubbles in the coolant ( mine doesn't burp and overflow, just a tiny stream of bubbles...but also, the expansion tank shouldn't be full cold....really just a bit below the fill neck)......and NOTHING abnormal in the engine oil analysis...then just keep using it till another symptom arises.

Hard to tell your problem if it isn't up to op temp and the coolant stops spilling out so you can just see bubbles in the tank.....then a pressure checker might come in handy if borrowed/rented from a auto parts store and you have the normal pressure cap upgrade on the expansion tank.
 
Comodave said:
I could not see the video since it wants me to sign in. But I would call Brian at American Diesel. He is the man as far as Lehmans go. 804-435-3107
Click to expand...

Agree. American Diesel are the go to guys for all things Lehman. They can diagnose problems over the phone better than most mechanics sitting in your engine room.
 
What if anything preceded the overheat? If you`ve had the boat for some time and until now the engine behaved itself, what changed? Did you top up coolant, was there a need to? Did you do anything else? It could just be air in the passages, opening the petcock with engine running will suck air according to the Lehman Manual I had.

Without the overflow tank the L120 does get rid of some coolant out of the header tank every use.
This doesn`t sound like your problem (at present) but the tube leading down from the header tank gets eaten away, eventually it leaks, just at head/block level, mimicking a head gasket leak. I have a spare L120 head gasket doing nothing at home.The fix is welding on a new length of al. tube to replace what the coolant has eaten.
 
The following is a great means to evacuate air from coolant system and fill it. The tool requires a compressor.

https://www.harborfreight.com/cooling-system-test-and-refill-kit-64985.html

You could also get a “leak down” tester to pressurize each cylinder to find an issue—more diagnostic possibilities than compression test. Also, get an infrared temp gun and take readings along each cylinder location and various points on the head and cooling circuit as it runs—write down the location abs temp for repeatability.

As everyone has said, the overheat needs to be determined. As you read, many individuals have had their raw water circuit foiled in unusual ways—for example, a Barnacle growing inside the through hull. Assuming a working seacock, pull the hose and open up to see if you’ve got full flow, then work your way through the circuit. Your initial cleanings sounded like they were all after the pump—if I missed that they weren’t, my apologies. Do make sure the seacock works effortlessly before doing the above.

And, Brian has been a lifesaver for me as I rebuilt one of my SP275s that had a non-recalled valve explode.

Much luck!
 
What does American Diesel recommend for coolant temperature? 120 F is low. Also, idling for as long as you do is hard on the engine especially with only 120F operating temps. For good engine health 180F oil temperatures should be attained as measured by an IR gun on the pan.
 
If you're having air in the coolant problems, drill a small hole, about 1/16" in the thermostat flange. It allows air to pass thru without effecting the normal operation of the thermostat.
In some engines, air gets trapped below the thermostat when filling. An air pocket below the thermostat doesn't transfer heat as well as water and the thermostat may not open before the engine starts to overheat. Several engines come with this type of thermostat with a hole in the flange.
For example, my Detroits have a 1/2" line that bypasses the thermostat and always ensures there is some coolant flow. The engines warms up fine.
I came to this conversation late, but the bubbling at the cap doesn't look to contain air, it's just the consequence of the thermostat opening with the engine completely full of coolant. Water expands when heated. In a proper setup, the overflow tube is connected to a small tank with a bottom feed. When the engine heats, the expanding coolant is pushed into the overflow tank. When it cools, creating a vacuum, it draws coolant from the tank, refilling the engine.
First I would take a compression test, if ok, descale the raw water side. If it still overheats, I'd descale the coolant side. I've fixed a lot of overheating engines, other yards threw customer's money at, by descaling the coolant side.
 
If you are getting water flow out from the exhaust is it cool, warm or hot? If cool yet engine coolant is hot I would suspect the engine water pump has a problem. I had a similar problem with a generator. I kept trying to find a problem on the seawater side. Impellers, heat exchanger...
Then I realized that there was no coolant flow so eng block just got hotter and hotter because coolant never was flowing thru the heat exchanger.
 
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