My Lehman coolant hose hack

Marco Flamingo · Oct 24, 2021

This project started out as the alternator hack using a turnbuckle as in other threads. While replacing the alternator arm with the turnbuckle, I noticed that my original arm was different than some. Some Lehmans have a curved arm that attaches to the lower bolt on the water pump and the alternator (second picture). That doesn't leave a "sneak route" for a coolant hose to avoid passing through the fan belt. By attaching the alternator turnbuckle to the upper bolt on the water pump, I thought I might be able to purchase off-the-shelf silicon hose pieces and fabricate a hose that allowed easier fan belt replacement.

I removed my original coolant hose and found that it was not in great shape. It appears that it had a wire coil inserted in it to keep the bends from collapsing. You can see the wire inside in the upper right in the first (sideways) picture. This isn't the wire imbedded in the rubber hose coming loose. It's a separate wire coil. The old hose ends were splitting, there were soft spots, and the cheese-grater style hose clamps had dug in fairly deep.

I also had an old fan belt wrapped around the coolant hose so that a fan belt could be replaced without removing the hose (the original Lehman hack to simplify replacing a broken belt). The belt was of unknown vintage. I thought that as long as I was replacing the coolant hose, I'd try a hack. The 4 red silicon hose bends and new clamps were less than $100. I didn't look to see what a new standard Lehman hose would be. I now have a new coolant hose and a fan belt that can be quickly replaced without the use of tools.

Cigatoo · Oct 24, 2021

Marco Flamingo said:
This project started out as the alternator hack using a turnbuckle as in other threads. While replacing the alternator arm with the turnbuckle, I noticed that my original arm was different than some. Some Lehmans have a curved arm that attaches to the lower bolt on the water pump and the alternator (second picture). That doesn't leave a "sneak route" for a coolant hose to avoid passing through the fan belt. By attaching the alternator turnbuckle to the upper bolt on the water pump, I thought I might be able to purchase off-the-shelf silicon hose pieces and fabricate a hose that allowed easier fan belt replacement.

I removed my original coolant hose and found that it was not in great shape. It appears that it had a wire coil inserted in it to keep the bends from collapsing. You can see the wire inside in the upper right in the first (sideways) picture. This isn't the wire imbedded in the rubber hose coming loose. It's a separate wire coil. The old hose ends were splitting, there were soft spots, and the cheese-grater style hose clamps had dug in fairly deep.

I also had an old fan belt wrapped around the coolant hose so that a fan belt could be replaced without removing the hose (the original Lehman hack to simplify replacing a broken belt). The belt was of unknown vintage. I thought that as long as I was replacing the coolant hose, I'd try a hack. The 4 red silicon hose bends and new clamps were less than $100. I didn't look to see what a new standard Lehman hose would be. I now have a new coolant hose and a fan belt that can be quickly replaced without the use of tools.

catalinajack · Oct 24, 2021

Marco Flamingo said:
This project started out as the alternator hack using a turnbuckle as in other threads. While replacing the alternator arm with the turnbuckle, I noticed that my original arm was different than some. Some Lehmans have a curved arm that attaches to the lower bolt on the water pump and the alternator (second picture). That doesn't leave a "sneak route" for a coolant hose to avoid passing through the fan belt. By attaching the alternator turnbuckle to the upper bolt on the water pump, I thought I might be able to purchase off-the-shelf silicon hose pieces and fabricate a hose that allowed easier fan belt replacement.

I removed my original coolant hose and found that it was not in great shape. It appears that it had a wire coil inserted in it to keep the bends from collapsing. You can see the wire inside in the upper right in the first (sideways) picture. This isn't the wire imbedded in the rubber hose coming loose. It's a separate wire coil. The old hose ends were splitting, there were soft spots, and the cheese-grater style hose clamps had dug in fairly deep.

I also had an old fan belt wrapped around the coolant hose so that a fan belt could be replaced without removing the hose (the original Lehman hack to simplify replacing a broken belt). The belt was of unknown vintage. I thought that as long as I was replacing the coolant hose, I'd try a hack. The 4 red silicon hose bends and new clamps were less than $100. I didn't look to see what a new standard Lehman hose would be. I now have a new coolant hose and a fan belt that can be quickly replaced without the use of tools.

Now that is one terrific mod. Those hoses look to be moulded. Can you share your sources for the indivudual hose sections?

Marco Flamingo · Oct 24, 2021

Starting from bottom to top, four sections all 1.75 inch: 135 degree, 45 degree, 90 degree, 180 degree. Your choice of colors.

I needed two splice barbs and a bunch of new hose clamps. Each of the first three sections had to have one leg shortened by about 1.25" and everything fit together. It does pass close to the alternator, but if there were contact it would be against a hose clamp band. Plus, the alternator has a temp sensor (210F max) that keeps it well below the hose temp rating (375F).

SteveK · Oct 24, 2021

I like the hack, will check to see if can be done on mine.

Meanwhile, should I need to change belts in a hurry a new belt is hanging from the rafters and looped around that hose in question. Just drop down and attach.

jleonard · Oct 24, 2021

Nice "hack"!

C lectric · Oct 24, 2021

Don'h have the problem, different engine,

BUT NICE HACK from here too.

catalinajack · Oct 24, 2021

Marco Flamingo said:
Starting from bottom to top, four sections all 1.75 inch: 135 degree, 45 degree, 90 degree, 180 degree. Your choice of colors.

I needed two splice barbs and a bunch of new hose clamps. Each of the first three sections had to have one leg shortened by about 1.25" and everything fit together. It does pass close to the alternator, but if there were contact it would be against a hose clamp band. Plus, the alternator has a temp sensor (210F max) that keeps it well below the hose temp rating (375F).

Thanks! I will be doing this as a winter project.

Alisske · Oct 24, 2021

100$? Great. Red color for cool factor.

Nice mod

READY · Oct 25, 2021

It seems like 2 splice barbs are not enough to join the 4 hose sections? Is it qty 3?

catalinajack · Oct 25, 2021

Marco Flamingo said:
Starting from bottom to top, four sections all 1.75 inch: 135 degree, 45 degree, 90 degree, 180 degree. Your choice of colors.

I needed two splice barbs and a bunch of new hose clamps. Each of the first three sections had to have one leg shortened by about 1.25" and everything fit together. It does pass close to the alternator, but if there were contact it would be against a hose clamp band. Plus, the alternator has a temp sensor (210F max) that keeps it well below the hose temp rating (375F).

More questions if I may.

1. Do you think your configuration would clear a conventional curved alternator mounting arm?
2. What is the length and thread size of the turnbuckle?
3. If your fan belt were an inch longer, would that not give you a bit more clearance to the alternator case?
4. What is the size, brand, and part number of the fan belt you used?
5. What is that black 1-inch (?) vertical hose to the right of the alternator?
6. The shortened sections, which first three sections, from the top or the bottom?

Marco, obviously your idea has sparked a lot of interest among us FL120 owners. Terrific idea.

psneeld · Oct 25, 2021

Are those silicone hoses wire reinforced?

Maybe the Lehman doesn't need wire reinforced hoses on the suction side of the water pump..... I don't know ....the mod does have a lot of bends to give some collapse resistance....but might worry about high rpm operations if not wire reinforced.

I used non wire reinforced on the far side of the expansion tank with no issues....did that to get rid of the brass tubing that made the injector pipe install difficult.

Marco Flamingo · Oct 25, 2021

catalinajack said:
More questions if I may.

1. Do you think your configuration would clear a conventional curved alternator mounting arm?
2. What is the length and thread size of the turnbuckle?
3. If your fan belt were an inch longer, would that not give you a bit more clearance to the alternator case?
4. What is the size, brand, and part number of the fan belt you used?
5. What is that black 1-inch (?) vertical hose to the right of the alternator?
6. The shortened sections, which first three sections, from the top or the bottom?

Marco, obviously your idea has sparked a lot of interest among us FL120 owners. Terrific idea.

1. I think it might be too close for a curved alternator arm that is hooked to the lower bolt on the water pump. One of the things that concerned me was having the silicon hose close to a sharp edge. My alt arm was sharp. The turnbuckle isn't and is far away.
2. I found that the measurements given for turnbuckles online was of little help. I found a #8 turnbuckle that fit. My guess is that even though the size is given in inches, the "#8" means an 8mm threaded section. It fits.
3. A longer fan belt might give me more room. Probably need to be several inches longer to make a difference. I'm just going to watch it close.
4. It's a Dayco cogged fan belt, but I don't remember the number. My foggy memory make me think 47," but I'll check next time at the boat.
5. The 1" black hose left unattached is the coolant return line from my hot water tank and bus heater. This is why I only needed two new barbs to connect 4 new pieces of hose. I already had one with a 1" T. The original takeoff connection piece was in front, like the original hose. Now the 1" return line connection is in the back facing aft. The new hose configuration also cleaned up the look of the takeoff hosing.
6. I think I misspoke. The first section (bottom 135 degree) had both legs shortened. That gave me the ability to make the quick turn to get between the block and the alternator. The next section (45 degree) had the lower leg shortened. This connection is made with the original 1" T for the hot water. The 90 and 180 are stock pieces. The legs on these silicon hose sections seem to vary by vendor, so my cut off amount isn't going to be universal.

I made some additional modifications while I was at it. My PO had a rat's nest of hose tubing and valves to feed the hot water tank (aft) and the bus heater (forward). I pulled all of that out and now have a single line that runs forward through the bus heater and then back through the hot water tank and then returns to the engine. I think it will flow a lot more and time will tell if the bus heater removes so much heat that the hot water tank won't get enough. If I start with 180 degree and the bus heater pulls that down to 130 and then travelling to the hot water tank is 120, the hot water will take a long time and not be all that hot (for dishes, it would be for showers). I can always turn the bus heater down or off, but time will tell if that is required.

Another modification that I made is a T in the 1" hose line at the lowest part in the bilge. I put in one of the PO's valves there. Next time I need to drain the coolant, I'll just open it up and drain into a five gallon bucket. No more flying green juice when I have to work on the coolant lines.

Marco Flamingo · Oct 25, 2021

psneeld said:
Are those silicone hoses wire reinforced?

They are not wire reinforced. They have 3 wrappings of polyester mesh imbedded in the silicon and are pressure rated (80 psi) for use with a turbo, but nothing is said as to the vacuum rating (which would also occur in a turbo setting, normally about 20 Hg). They are less squishy than the hose that was replaced, but I guess I should do a hot WOT test to see if anything changes.

psneeld · Oct 25, 2021

Thank, just wanted everyone to know that it is a consideration, but how much so,I too am curious.

I never run above 1800 so I would never have to worry, but the next owner might get surprised if it is necessary.

catalinajack · Oct 25, 2021

As for the wire coil, one could simply remove the one from the original hose and insert it in the new assembly.

psneeld · Oct 25, 2021

catalinajack said:
As for the wire coil, one could simply remove the one from the original hose and insert it in the new assembly.

Those are usually just for bends, not longer lengths....might work in this case or it's just better to order wire reinforced hose if needed.

Gdavid · Oct 25, 2021

psneeld said:
Those are usually just for bends, not longer lengths....might work in this case or it's just better to order wire reinforced hose if needed.

It generally isn't needed on the coolant side of the system as the pressure of the system by the time the thermostat opens, is high enough that even the suction end of the pump is above atmospheric pressure. Circulating pumps don't create a large pressure differential because they arent working against much resistance. On automobiles, the spiral is only needed when making tight turns and automotive coolant hoses are pretty flimsy comparted to most marine applications.

catalinajack · Oct 26, 2021

Marco Flamingo said:
1. I think it might be too close for a curved alternator arm that is hooked to the lower bolt on the water pump. One of the things that concerned me was having the silicon hose close to a sharp edge. My alt arm was sharp. The turnbuckle isn't and is far away.

2. I found that the measurements given for turnbuckles online was of little help. I found a #8 turnbuckle that fit. My guess is that even though the size is given in inches, the "#8" means an 8mm threaded section. It fits.

3. A longer fan belt might give me more room. Probably need to be several inches longer to make a difference. I'm just going to watch it close.

4. It's a Dayco cogged fan belt, but I don't remember the number. My foggy memory make me think 47," but I'll check next time at the boat.

5. The 1" black hose left unattached is the coolant return line from my hot water tank and bus heater. This is why I only needed two new barbs to connect 4 new pieces of hose. I already had one with a 1" T. The original takeoff connection piece was in front, like the original hose. Now the 1" return line connection is in the back facing aft. The new hose configuration also cleaned up the look of the takeoff hosing.

6. I think I misspoke. The first section (bottom 135 degree) had both legs shortened. That gave me the ability to make the quick turn to get between the block and the alternator. The next section (45 degree) had the lower leg shortened. This connection is made with the original 1" T for the hot water. The 90 and 180 are stock pieces. The legs on these silicon hose sections seem to vary by vendor, so my cut off amount isn't going to be universal.

I made some additional modifications while I was at it. My PO had a rat's nest of hose tubing and valves to feed the hot water tank (aft) and the bus heater (forward). I pulled all of that out and now have a single line that runs forward through the bus heater and then back through the hot water tank and then returns to the engine. I think it will flow a lot more and time will tell if the bus heater removes so much heat that the hot water tank won't get enough. If I start with 180 degree and the bus heater pulls that down to 130 and then travelling to the hot water tank is 120, the hot water will take a long time and not be all that hot (for dishes, it would be for showers). I can always turn the bus heater down or off, but time will tell if that is required.

Another modification that I made is a T in the 1" hose line at the lowest part in the bilge. I put in one of the PO's valves there. Next time I need to drain the coolant, I'll just open it up and drain into a five gallon bucket. No more flying green juice when I have to work on the coolant lines.

As to draining coolant on a FL120, mine have a petcock on the side of the block with the alternator. I simply attach some tubing leading to a five-gallon bucket, open the petcock, and loosen the radiator cap. Come back 15 minutes later and the engine is empty of antifreeze.

Marco Flamingo · Oct 26, 2021

I also have that petcock on the side of the block. Problem is that it that while it can slowly empty the block it doesn't empty any hot water using accessories or the lines to them. My new inline valve is at the lowest point for my whole system. One thing that I learned from refilling is to open the petcock on the manifold. The coolant will slowly (very slowly) drain down through a thermostat without doing that. Or, you can run the engine to get it hot enough to open the thermostat. Even just running the engine was quite slow, probably because there wasn't coolant running through the system. Opening the manifold petcock allowed me to put coolant in faster. There probably is a "proper way," but I don't know what it is.

catalinajack · Oct 26, 2021

Marco Flamingo said:
I also have that petcock on the side of the block. Problem is that it that while it can slowly empty the block it doesn't empty any hot water using accessories or the lines to them. My new inline valve is at the lowest point for my whole system. One thing that I learned from refilling is to open the petcock on the manifold. The coolant will slowly (very slowly) drain down through a thermostat without doing that. Or, you can run the engine to get it hot enough to open the thermostat. Even just running the engine was quite slow, probably because there wasn't coolant running through the system. Opening the manifold petcock allowed me to put coolant in faster. There probably is a "proper way," but I don't know what it is.

I open the manifold petcock when both draining and filling. My water heater sits on a shelf above the level of the engine so it can drain via the petcock. My thermostats have 1/8-inch holes to allow air to pass which also faciltates draining and filling. The holes do not inhibit engine warmups.

DW1979OA · Oct 29, 2021

This is a brilliant hack. Thanks for sharing. Just wish it was 2 months ago when I changed out my belts. So many great observations by others too.
I have the further complication of the PTO for the hydraulic stabilizer attached to the harmonic balancer. Hope not to need to go thru the effort again but keeping a copy of this posting printed and handy
jp

catalinajack · Nov 2, 2021

Warning on the coolant hack - Marco did not mention that the bottom-most hose piece is 2-inch hose while the succeeding hose is 1.75 inches. You will need a reducing coupler rather than a straight coupler. I found them at Filter Neck Supply. I haven't finished the installation, of course, but it looks like it will be fairly easy to complete. You will need the turnbuckle and a longer alternator belt. The turnbuckle is quite simple. You will need a few washers to cover the large eye and perhaps different length bolts for the water pump. The bolt size is 5/16-18 course thread.

Marco Flamingo · Nov 2, 2021

My hose is 1.75" throughout on a Lehman 80 hp. A 2 inch hose will have a slightly different geometry and won't allow for as tight of a turn even though the bend is 135 degrees (unless the legs can be cut real short). I have a black 2 inch 135 bend (purchased by mistake) that I'll send for shipping cost.

I've only found a couple of minor things that differ between the 120 and the 80, and those might not be universal differences. Maybe the water pump is different between the two, although I can't think of why Lehman (or Ford) would go to the trouble.

I forgot to look at my belt length yesterday. Maybe I'll remember today.

catalinajack · Nov 2, 2021

Marco Flamingo said:
My hose is 1.75" throughout on a Lehman 80 hp. A 2 inch hose will have a slightly different geometry and won't allow for as tight of a turn even though the bend is 135 degrees (unless the legs can be cut real short). I have a black 2 inch 135 bend (purchased by mistake) that I'll send for shipping cost.

I've only found a couple of minor things that differ between the 120 and the 80, and those might not be universal differences. Maybe the water pump is different between the two, although I can't think of why Lehman (or Ford) would go to the trouble.

I forgot to look at my belt length yesterday. Maybe I'll remember today.

Sorry Marco, I did not realize that your engine is a FL80. On a 120, the hose from the header tank is two inches in diameter while the water pump is 1.75 inches. The standard molded hose has the correct ends. I already have a two-inch 135-degree elbow and have cut it down by 1.25 inches and I have dry-fit the other pieces with no cuts. I am confident I can make it work nicely
with some trimming but I need the 2-1.75 inch coupler to continue the project. I have also ordered a longer alternator belt which will give me the clearance I need between the hose assembly and the alternator case. A longer belt is definitely needed. By the way, the turnbuckle works like a champ, easily fit. I did need to shim it out from the water pump with three thin washers to get it parallel with the alternator case. Interestingly, the connector/tap I have for the water heater line is indeed 2-inches on one side and 1.75 inches on the other.

Marco Flamingo · Nov 2, 2021

My alternator belt is 47 x .5 inch. Here is a picture comparing the 1.75" and the 2" 135 degree silicone hose bend. The picture exaggerates the width a little (and the legs on the black 2" haven't been shortened), but it would have made my hack a little more complex.

catalinajack · Nov 4, 2021

Okay, folks, I got Marco's plumbing to work on a FL120. I had to use a longer fan belt to get the alternator to clear the hose by 1/2 inch. I used a Dayco #17490. A turnbuckle rather than a curved arm is a must.

Dixie Life · Dec 2, 2021

Great! Where did you get the hoses?

catalinajack · Dec 2, 2021

Dixie Life said:
Great! Where did you get the hoses?

Follow the links in Post #4.

Dixie Life · Dec 2, 2021

Got it. Thanks Jack.

My Lehman coolant hose hack

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