FL 120 Coolant Leak

[Captain K]

Lately I've noticed a small amount of coolant around the filler neck on the expansion tank of my port engine, a Ford-Lehman 120 with just over 3,000 hours. I clean it up, but it reappears after a few hours running. A check of the coolant in the tank after the engine cools down shows no noticeable drop in level. And the engine seems to be running at proper temps. I suspect this may be an early sign that my head gasket needs replacing. Your thoughts?

 

[psneeld]

Mine does the same...has from day one after buying the boat...the engine was a rebuilt with only 200 hrs on it when I bought it.

I'm curious too as previous advice t me was that it was common, switch to the recovery neck from AD and watch closely.

I have watched, wondered, put over 800 hrs on the engine back and forth to Florida and am still wondering. No other symptoms of blown head gasket...oil analysis good, no bubbles in filler neck with engine running, exhaust seems normal for a Lehman (do have to check it's odor next time), coolant loss is in ounces if I haven't filled to tank to the bottom of the neck...seems that when I do...that's the biggest loss days.

 

[Capt.Bill11]

Maybe the cap is weak. Or you are trying to keep the expansion tank to full.

Lehman's seem to like to run with the fluid level in the tank about an inch or so from the top. If you over fill it. it just expands it out till it finds it's happy level. Hence the term expansion tank.

I would not jump right to a head gasket issue.

 

[Anthonyd]

I would use a pressure tester on the cap and see if it holds at the rated system pressure. If it does then the cap is good. Then test the system cold at rated pressure. Then test hot and compare the two. Then go from there. I agree with Capt.Bill11 and would not jump to a head gasket especially since you stated that you did not see bubbles in the coolant. Radiator Pressure Tester Kit
This is just one example of a kit you can get.

 

[psneeld]

Maybe the cap is weak. Or you are trying to keep the expansion tank to full.

Lehman's seem to like to run with the fluid level in the tank about an inch or so from the top. If you over fill it. it just expands it out till it finds it's happy level. Hence the term expansion tank.

I would not jump right to a head gasket issue.

Seems right to me...I though the "coolant level" per my manual says higher...but I think my engine disagrees. The image is what the manual says...

I'm not so sure that the cap is correct or maybe there is something warped/gasket issue or incorrect cap because I think coolant is coming from under the cap. I do have a tube to a plastic expansion tank from the discharge port under the cap. Have to play with it a bit or just order one from AD.

 

[Ski in NC]

Cap filler neck, if brass, is rather flimsy and someone probably stepped on it, bending it. Once bent, cap won't seal. Replacement necks are available and can be epoxied in. Also, the al tank might get pitted next to the brass. Either way, a new neck glued in will fix it.

There are different ways the neck is installed, but since tank is al, it is not soldered on.

Lower coolant level and heat up neck with a torch and glue lets go.

 

[Xsbank]

Buy the coolant overflow kit from American Diesel. It's easy to fit and no more coolant loss. The Lehman chooses its own level and the coolant overflow tank is the only way to stop the cleanup.

Your head gasket is happy.

 

[Capt.Bill11]

The Lehman chooses its own level and the coolant overflow tank is the only way to stop the cleanup.

Not really. If all is working correctly and you don't keep overfilling the tank there is normally no overflow to clean up. But a overflow tank is nice to have. You can save yourself some money if you wish but just putting a empty coolant jug with a hole in the top down in your engine drip pan and run a hose from the expansion tank overflow tube to it for a poor mans overflow tank.

This would be a good time to point out the petcock that older Lehmans have on top of the manifold that allows you to bleed out any air that gets trapped due to the angle that the engine is mounted at. This should be opened and bled any tin you check the fluid level in the expansion tank. The new Lehman's have a braided line that goes from the manioc to the expansion tank to make it self bleeding. And yes you can rig that up to an older Lehman if you wish.

I mention this because I am surprised by how many people I run into with Lehman's who don't know what this petcock is for.

 

[psneeld]

Not really. If all is working correctly and you don't keep overfilling the tank there is normally no overflow to clean up. But a overflow tank is nice to have. You can save yourself some money if you wish but just putting a empty coolant jug with a hole in the top down in your engine drip pan and run a hose from the expansion tank overflow tube to it for a poor mans overflow tank.

This would be a good time to point out the petcock that older Lehmans have on top of the manifold that allows you to bleed out any air that gets trapped due to the angle that the engine is mounted at. This should be opened and bled any tin you check the fluid level in the expansion tank. The new Lehman's have a braided line that goes from the manioc to the expansion tank to make it self bleeding. And yes you can rig that up to an older Lehman if you wish.

I mention this because I am surprised by how many people I run into with Lehman's who don't know what this petcock is for.

Knew about bleeding..haven't heard or have seen the auto-bleed you are talking about sounds like the ticket though.

Anything special to do, don't do? Any published source for step by step/materials list/suppliers?

That would be much appreciated and others too may be interested.

 

[RT Firefly]

Greetings,
Mr. 111. I'd be very interested in that modification as well please.

 

[meridian]

If the coolant level is still at the top it isn't an issue of finding its own level. You may hsve a small leak in your heat exchanger. Pull it and have it pressure tested.

 

[Capt.Bill11]

Well you just replace the petcock with a nipple fitting, drill and tap a hole in the rear upper portion of your expansion tank for another nipple fitting. As I mentioned on the newer Lehman's they use braided line and with flared swivels ends that thread onto the threaded flair nipples. But you could use a different type of hose and hose clamps clamped to plain hose nipples.

There is a way to make your CAV fuel filters self bleeding as well if anybody is interested.

 

[Captain K]

Capt.Bill11...I was not aware of air bleeding until reading your post, then finding it in my FL Operator's manual. Wow, maybe that's what I need to do? Will give it a go. Comforting comments from those posting who suggest my issue may not be head gasket related. I already have the fancy overflow tanks. They were in place when I purchased the boat. But they never seem to get any coolant in them from the expansion tanks on either engine, which I find curious. Then again I'm not exactly conversant with how they work. Wish somebody would publish a FL Owners Manual for Dummies...like me! Meantime am saving my coins to take one of Bob Smith's courses?

 

[psneeld]

Well you just replace the petcock with a nipple fitting, drill and tap a hole in the rear upper portion of your expansion tank for another nipple fitting. As I mentioned on the newer Lehman's they use braided line and with flared swivels ends that thread onto the threaded flair nipples. But you could use a different type of hose and hose clamps clamped to plain hose nipples.

There is a way to make your CAV fuel filters self bleeding as well if anybody is interested.

Not being picky or ungrateful because I do appreciate your info here..

There is a warning not to open the petcock to bleed while the engine is running.... as air may be introduced rather than expelled.

That would have me think that the lead to the expansion tank should go below the fluid level...even if it's low...

Any warnings there ? ....as you mentioned the upper portion for the tap. Probably hot the fluid should be up near the cap anyway...but if it wasn't, do you think that low or on the bottom of the expansion tank would be better?

 

[Capt.Bill11]

Not being picky or ungrateful because I do appreciate your info here..

There is a warning not to open the petcock to bleed while the engine is running.... as air may be introduced rather than expelled.

That would have me think that the lead to the expansion tank should go below the fluid level...even if it's low...

Any warnings there ? ....as you mentioned the upper portion for the tap. Probably hot the fluid should be up near the cap anyway...but if it wasn't, do you think that low or on the bottom of the expansion tank would be better?

No problem.

Air can't be introduced in the system with the bleeder because the system is close while running.

As to the location of the fitting on the tank, it's been quite a few years but as I remember it you drill the hole based on where the "factory" bleeder goes into the tank. And as I recall it's towards the top of the tank so the air will flow up and out of the manifold and then into the tank. But my memory of the exact location of the factory fitting could be faulty. I'd have to look at one to double check.

 

[psneeld]

No problem.

Air can't be introduced in the system with the bleeder because the system is close while running.

As to the location of the fitting on the tank, it's been quite a few years but as I remember it you drill the hole based on where the "factory" bleeder goes into the tank. And as I recall it's towards the top of the tank so the air will flow up and out of the manifold and then into the tank. But my memory of the exact location of the factory fitting could be faulty. I'd have to look at one to double check.

Still wondering because it seems like the warning about opening the manifold petcock letting air in is because the top of the manifold is under suction from the circ pump...

If the expansion tank gets hot and puts the air in there under some pressure yet the coolant never gets as high as the bleed line...I'm not sure but it would seem it would stay airlocked.

That's why I want to make sure I get it correct...not that I'm right about the suction and airlock...just don't want any issues when I have none but this sounds like a great mod....easy to forget to bleed that sucker every time!!!!

 

[Capt.Bill11]

If a pump is running in a closed loop does it really create any suction? Or is it, as the name implies, just circulating the water and pushing it?

I found a picture: http://images.boats.com/resize/1/4/52/4090452_20130130083441402_1_LARGE.jpg

The location is as I remember it.

 

[BruceK]

Start with the cap, for the original tank design it is a mighty 4 psi, and available from AD. I replaced both of mine, coolant loss pretty much stopped.

 

[psneeld]

If a pump is running in a closed loop does it really create any suction? Or is it, as the name implies, just circulating the water and pushing it?

I found a picture: http://images.boats.com/resize/1/4/52/4090452_20130130083441402_1_LARGE.jpg

The location is as I remember it.

 

[Jbear]

Capt. K, no disrespect intended but I would hurry up in taking one of Bobs classes. He has been working on these for a long time. He has a couple of health issues he spoke of during our class.

Jeff

 

[jleonard]

I had a "pesky" coolant leak around the filler cap for a couple of years. Not much would leak, but there was always anti-freeze in the groove around the top of the expansion (aka Header) tank.
I finally fixed the problem. The extended neck is epoxied in place when the mod is done. That epoxy had developed a small crack.
I ground it out a little with a dremel, cleaned it and gooped it up with some epoxy and the leak is fixed.

 

[Peter B]

Maybe the cap is weak. Or you are trying to keep the expansion tank to full.

Lehman's seem to like to run with the fluid level in the tank about an inch or so from the top. If you over fill it. it just expands it out till it finds it's happy level. Hence the term expansion tank.

I would not jump right to a head gasket issue.

Absolutely right. Mine does exactly the same. If I only fill to about that inch below the neck, as bill says, no loss. When the cap fell to bits recently I thought I might have trouble sourcing a new 4lb pressure one here in Oz, so emailed American Diesel, and they were ready to ship me the recycling type of neck adaptor and cap, but it was going to cost about $100 all up. Then I found a replacement cap locally for $12, so thought what the heck, and left it at that. I only have to add coolant about once a year anyway.