Ford Lehman 135sp coolant question

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paulga

Guru
Joined
May 28, 2018
Messages
1,397
Location
United States
Vessel Name
DD
Vessel Make
Marine Trader Sundeck 40'
The water level in the coolant reservoir is already lower than the Add mark. Last November it was somewhere between the Add and the Full mark.
I want to add some coolant and keep monitoring, but have no clue what coolant should be used.
I remember the color is pink from the surveyor's coolant tester. Is this enough information to determine what coolant to buy?


Image_20240805180459.jpg
 
Probably not enough just to go by color. I am not on my boat so don't have access to the service manual but maybe someone will.
My suggestion is if you don't know when it was last changed or when the heat exchanger was serviced perhaps take this opportunity to drain, flush and fill with new of the correct type. Not an expensive or difficult job. Now you will have a baseline.
 
READY said:
Probably not enough just to go by color. I am not on my boat so don't have access to the service manual but maybe someone will.
My suggestion is if you don't know when it was last changed or when the heat exchanger was serviced perhaps take this opportunity to drain, flush and fill with new of the correct type. Not an expensive or difficult job. Now you will have a baseline.
Click to expand...
the coolant system was flushed last year. I remember seeing some bottles in the bilge that could be either engine oil or coolant.
I wouldn't mind flushing it again but have not found a tutorial how to drain and flush the coolant system on this specific engine.
 
Hey Paulga,

If you find instructions re flushing the cooling system on your Lehmans - please post it here - I would be keen to see/follow it.
 
If you have some bottles on board then go with that type. If not then I would drain, flush and refill as suggested above.
 
Comodave said:
If you have some bottles on board then go with that type. If not then I would drain, flush and refill as suggested above.
Click to expand...

PO stored 4 bottles of engine oil, 3 bottles of coolant and 2 bottles of transmission fluid in the bilge
they are mostly full and still sealed, not empty as I thought
each bottle was marked the number "23" probably indicating the purchase year

so the "final charge" is the antifreeze coolant. Clearly, the plastic reservoir is the place to top off as it's higher than the engine. Is the metal bracket supposed to be unscrewed from the bulkhead to release the plastic reservoir? should I add coolant to the full mark?


IMG20240808195719.jpg


IMG20240808200108.jpg
 
When I had Lehmans I used to top off at the header tank cap. Even after I fitted expansion bottles. There is a petcock on the manifold you open when topping up, when it overflows you are full.
I would not top up the plastic expansion bottle to the top level. It`s intended to drain back as the engine cools and fill as the engine heats, you expect the level to vary.
 
The overflow bottle should have a hot full mark and mine have a low cool mark. I fill mine to the cool mark and when the engine heats up and the coolant expands it will go up to about the hot full mark. Don’t top it up to the hot mark when it is cool as it may overflow when it gets hot.
 
The coolant in the overflow is Extended Life Coolant. (ELF). From my experience with the same 135 and the same overflow bottle you will get a large swing in the level in the bottle based on engine temp and even ambient temperature. The full mark is not a precise indicator. As long as there is coolant present in the bottle with a cold engine you are fine. As the engine warms the level in the bottle will rise. You will notice as weather starts to get cooler in the fall, the bottle as it stands now will be empty when engine is cold. If you should find it empty just add a few inches and run the engine up to operating temp. This will purge any air. Obviously if you continuously find it emptying out you have a leak.
 
BruceK said:
When I had Lehmans I used to top off at the header tank cap. Even after I fitted expansion bottles. There is a petcock on the manifold you open when topping up, when it overflows you are full.
I would not top up the plastic expansion bottle to the top level. It`s intended to drain back as the engine cools and fill as the engine heats, you expect the level to vary.
Click to expand...

is this the petcock on the manifold for topping up?
the plastic bottle is at a higher level and has fluid in it, so the manifold thing should already be full?

IMG20240808200436.jpg
 
The 135 does not have the bleeder petcock on the exhaust manifold, the 120 does have it. Paul, what you have circled is the main coolant fill port on the coolant reservoir. If you change fluid it would be much easier to add it through this.
If you are just topping up you may be able to pump some into the expansion tank without removing it, otherwise yes you will have to take it off the wall.
 
av8r said:
The 135 does not have the bleeder petcock on the exhaust manifold, the 120 does have it. Paul, what you have circled is the main coolant fill port on the coolant reservoir. If you change fluid it would be much easier to add it through this.
If you are just topping up you may be able to pump some into the expansion tank without removing it, otherwise yes you will have to take it off the wall.
Click to expand...
just topping up this time if necessary, as the coolant side system was flushed last year
what pump can I use to add to the expansion tank?
 
I like this pump for things like that. It costs $20 on Amazon.

Sierra Electric Tools JB5684 Battery Operated Liquid Transfer Pump​

 
Comodave said:
I like this pump for things like that. It costs $20 on Amazon.

Sierra Electric Tools JB5684 Battery Operated Liquid Transfer Pump​

Click to expand...
this looks like a great low cost option.
this hand priming pump is what I already have - does this work?

6133uk9b5YL._AC_SL1000_.jpg
 
The squeeze pump will work or Harbor Freight sells a cheap “Fluid Transfer Pump” for unser $10 that works. A detergent bottle with a hose on it might work.
 
av8r said:
The squeeze pump will work or Harbor Freight sells a cheap “Fluid Transfer Pump” for unser $10 that works. A detergent bottle with a hose on it might work.
Click to expand...

on top of the heat exchanger near the end cap there is a bolt with copper hex head where the PO marked "6 23".
is this the zinc pencil that was changed last June?
How to inspect to decide it should be changed?

IMG20240812005326.jpg
 
That is the zinc anode. Common wisdom is to replace it when it is 50% gone, but that’s not really very helpful.
The brass nut has a zinc rod with threads that screws into the nut part, and those rods are available in 2 sizes, 1/2” and 5/16”. The 1/2” are famous for getting stuck in the heat exchanger which requires you to take off the end plate to remove it which requires that you have a new gasket, etc. The smaller size does not get stuck.
I change mine every 2 years, around 200 hours of operation.
 
av8r said:
That is the zinc anode. Common wisdom is to replace it when it is 50% gone, but that’s not really very helpful.
The brass nut has a zinc rod with threads that screws into the nut part, and those rods are available in 2 sizes, 1/2” and 5/16”. The 1/2” are famous for getting stuck in the heat exchanger which requires you to take off the end plate to remove it which requires that you have a new gasket, etc. The smaller size does not get stuck.
I change mine every 2 years, around 200 hours of operation.
Click to expand...

Does the brass part have UNC thread? What is the target torque for installing the brass part on the heat exchanger?

This thread is relevant.

zinc-jpg.96448
 
NPT fittings— finger tight + 2-3 turns using tape or sealant. Some say don’t use sealant on the anodes to make sure there is electical contact, some say the sealant won’t insulate the brass plug and should be used so the anode can be removed.
For what it’s worth guage manufacturer VDO specifies no sealant or tape on its pressure and temperature senders that ground through the block.
 
av8r said:
NPT fittings— finger tight + 2-3 turns using tape or sealant. Some say don’t use sealant on the anodes to make sure there is electical contact, some say the sealant won’t insulate the brass plug and should be used so the anode can be removed.
For what it’s worth guage manufacturer VDO specifies no sealant or tape on its pressure and temperature senders that ground through the block.
Click to expand...
Got it. Thread dope may be necessary to prevent leak.

There are two pipe plugs at the bottom of the heat exchanger. Which one drains sea water and which drains coolant? Are both also NPT so should also install with sealant?


IMG_20240813_203237.jpg
 
B is seawater, I think but can’t confirm that A is coolant.
 
av8r said:
B is seawater, I think but can’t confirm that A is coolant.
Click to expand...
Thanks.
It was mentioned the port side of the block near the alternator has a coolant drain cock. This is the port side of the block. Which fitting is it?

IMG20240812004524.jpg
 
The small square-head plug above and between the oil pressure switch and sender is installed where a drain petcock frequently is.
 
av8r said:
The small square-head plug above and between the oil pressure switch and sender is installed where a drain petcock frequently is.
Click to expand...
So the drain cock is not installed. It's not a big deal considering the coolant flush is not done yearly. I remember this fitting can be connected to domestic hot water heater to utilize engine heat. What parts are needed for that setup?

Edit: this is already covered well in this video. it seems it has to be a hydronic water heater to make the connection: www.youtube.com/watch?v=7mkX9W9CILI
 
Last edited:
paulga said:
is this the petcock on the manifold for topping up?
the plastic bottle is at a higher level and has fluid in it, so the manifold thing should already be full?

View attachment 157137
Click to expand...
Your plastic tank is an overflow tank, meaning when coolant get hot in your main tank it will expand and extra volume will overflow to this plastic bottle. When cooling down it will contract and level in this plastic bottle will go down.
Just keep it between min and max (and do not max it when cold) and you will be good.

L
 
this fitting is a close up of the fitting above the battery below the plug in post #23
does this include two sensors? what's their functions?

IMG20240812004703.jpg
 
Those are most likely oil pressure sensors. The big one is likely the sender for the gauge at the helm, the small one is a low pressure switch for the engine alarm buzzer.
 
rslifkin said:
Those are most likely oil pressure sensors. The big one is likely the sender for the gauge at the helm, the small one is a low pressure switch for the engine alarm buzzer.
Click to expand...
Thanks.
then this one must be oil temp sender.
does the antifreeze coolant system have a thermostat and pump?

IMG20240812004752.jpg
 
The item in the photo is probably an oil pressure switch wired to the alternator field.
The coolant pump is on the front of the engine dricen by the same belt that turns the alternator. The thermostat is underneath the coolant reservoir and is accessed by removing the tank.
 
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