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Old 11-18-2010, 05:44 PM   #61
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RE: How Many Ford Lehmans are there?

Went down to the Boat last night and checked the valve on the side of the engine and it seemed to be fine, ie not clogged up. There appears to be no seperate valve on the Heater Exchange nor a seperate themostsat on the water heater. The stb engine takes about 10-15 minutes longer than the prt to come up to operating temp.

After reading one of the posts concerning the anodes in the Heater exchange I decided to take a look & promptly dropped the anode(what was left of it) into the Heater Exchange itself, so I took off the end plate to retrieve the anode and found the remains of a few old anodes that seemed to have suffered the same fate. I noticed the perferated plate on this inside of the Heater Exchange is some what restricted due to lime scale build up.Should I give it a rinse lime scale remover or is that a no no?

I am somewhat in awe of the technical knowledge that some of you guys have and at the same time quite realistic of my own technical ability so I like to take these things slowly and think each process through.

I am looking at my origional Lehman manual and the welcome letter on the inside of the front cover by one Robert J Smith reads "Perhaps the most important single recomendation I can make to the new engine owner is'do not tinker'if the unit is running well -leave it alone. Unless you what you are doing ,keep your hands off". Ever time I venture into the engine bay I feel the ghost of Robert J Smith looking over my shoulder.Still it's all fun(until I break something)
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Old 11-18-2010, 06:07 PM   #62
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RE: How Many Ford Lehmans are there?

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shrimp wrote:

Ever time I venture into the engine bay I feel the ghost of Robert J Smith looking over my shoulder.Still it's all fun(until I break something)
Bob probably wouldn't like that comment too much--- he's not dead * At least he wasn't as of not long ago.

He and his son Brian run American Diesel today which if you don't know is*the knowledge center of all things Lehman and the best source of parts.* Bob did much of the original marinization work for Lehman.

*
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Old 11-18-2010, 07:39 PM   #63
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RE: How Many Ford Lehmans are there?

Quote:
shrimp wrote:The stb engine takes about 10-15 minutes longer than the prt to come up to operating temp.
Still sounds like the thermostat in the engine is either not working correctly or stuck open.

Easy enough to check.* Even if the water heater was blocked totally I don't think it would effect the engine temp.* That is a by pass not a part of the cooling system per say.*
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Old 11-18-2010, 08:49 PM   #64
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How Many Ford Lehmans are there?

If the engine thermostat was not working this would affect the engine's temperature. I get the impression that the engine is reaching normal operating temperature. It would not do this if the thermostat was faulty in some way. If the engine thermostat was stuck open and not allowing the coolant temperature to reach the normal level, thus not heating the hot water heater sufficiently, the engine itself would be running too cool.

It takes about 20 to 30 minutes at normal cruise power for our starboard engine to get up to the same coolant temperature as the port engine because of the massive*extra heat exchanger on that engine*that is the ten gallon hot water tank. If the starboard engine's coolant thermostat was not operating correctly by being stuck full open the engine coolant temperature would never get anywhere near normal operating temperature and this would be reflected in the starboard engine's temperature gauge.

If the water heater's coolant loop is blocked, you're right, it would not affect the operating temperature of the engine.* But it would definitely affect how fast the engine reached operating temperature.* When we replaced the water heater in our boat a number of years ago*there was a period of time when we had no water heater at all*because I was rebuilding and reinforcing the shelf in the aft head that supports it.* But we still wanted to use the boat.*

So I simply blanked off the two coolant lines from the engine.* With no water heater in the loop, the starboard engine went up to operating*temperature at the same rate as the port engine.* When the new water heater was installed and connected, the starboard engine went back to taking 20-30 minutes to reach operating temperature at cruise power.


-- Edited by Marin on Thursday 18th of November 2010 09:57:44 PM
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Old 11-19-2010, 03:36 AM   #65
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RE: How Many Ford Lehmans are there?

So now Andy has to answer if the engine itself is getting to temp or is it the water heater that isn't getting to temp.* Slow or fast isn't really that relevant.

The Anode is not effecting it.* It is in the inner part of the heater and the engine coolant and the Anode do not interact.
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Old 11-19-2010, 04:28 AM   #66
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RE: How Many Ford Lehmans are there?

It takes about 20 to 30 minutes at normal cruise power for our starboard engine to get up to the same coolant temperature as the port engine because of the massive extra heat exchanger on that engine that is the ten gallon hot water tank.

Sounds like the HW heater is not properly installed in the cooling loop, and has to heat the 10-20G of HW before the engine thermostat sees the coolant.

Replumb so the HW heater is AFTER the thermostat.
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Old 11-19-2010, 01:47 PM   #67
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RE: How Many Ford Lehmans are there?

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So now Andy has to answer if the engine itself is getting to temp or is it the water heater that isn't getting to temp.
He did that already.* From his earlier post:* "The stb engine takes about 10-15 minutes longer than the prt to come up to operating temp."

This is the same temperature performance we experience on our GB with the starboard engine sending coolant to the hot water heater only for us it's about a 30 minute lag behind the port engine.* But we have a large water heater and long hose runs between the water heater and the engine.* So it will take longer to heat the water, during which time the water heater is acting like a heat exhanger for the engine's coolant and delaying it's rise to normal operating temperature.

If the water heater's coolant coils or pipes*were blocked or partially blocked, the circulation of coolant through the water heater would be restricted and so the engine would reach operating temperature faster than it would without the restriction.

*
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Old 11-20-2010, 05:23 AM   #68
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RE: How Many Ford Lehmans are there?

Quote:
FF wrote:

Sounds like the HW heater is not properly installed in the cooling loop, and has to heat the 10-20G of HW before the engine thermostat sees the coolant.

Replumb so the HW heater is AFTER the thermostat.
Marin,

FF is correct.* The thermostat is in an engine to insure that the engine gets to the proper operating temp*ASAP then service all additional items*as water temp allows while maintaining the engine at the proper temp.*So depending on where the sensor is reading the temp this may or may not be happening.* *
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Old 11-20-2010, 10:47 AM   #69
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How Many Ford Lehmans are there?

Our hot water heater is connected AFTER the engine's thermostat but it still acts like a second heat exchanger on the engine. Think about it. It doesn't make any difference where the coolant loop leaves and enters the engine relative to the thermostat. The fact is that coolant is sent off to circulate through this giant heat exchanger which cools it down until the hot water heater is up to temperature. The coolant coming back to the engine from the colder hot water heater has been cooled down, and this drops the temperature of the coolant it's mixing with in the engine. This is going to happen no matter where you take the coolant from or where you return it to relative to the engine's thermostat. As long as the hot water heater is part of the loop the coolant goes through, it's going to cool down the coolant it's mixed with back in the engine until the water in the water heater has warmed up enough to not drop the coolant temperature lower than the thermostat can deal with. Doesn't matter if you take it before the engine thermostat or after it.

Everybody I've talked to with a twin engine boat with the hot water heater attached to one engine has the same situation as we do. The engine with the hot water heater in its cooling loop takes longer to get to operating temperature than the one without the hot water heater in the loop.

It's no different than driving a car in cold weather. If it's cold out, the car takes longer to come up to temperature than when it's hot out. Why? Because the coolant is getting cooled a lot more by the radiator when the air is cold. It's got nothing to do with the thermostat, it's got every thing to do with how much heat is being taken out of the coolant by the radiator. Just like having an "extra" heat exchanger in the cooling loop of a boat engine, which is what the hot water heater is.

An extreme example in vehicles is when they're operated in very cold temperatures.* The cooling effect on the radiator is such that it overwhelms the thermostat's ability to regulate the engine's temperature and the only answer is to restrict the airflow through the radiator.* Hence the radiator covers you see on trucks up north in the winter, and the "window shade" radiator shield that was on older Volvos.* In the boat, that big, cold, hot water heater is like that real cold air hitting the radiator.* There's little the thermostat can do about it until the water in the hot water heater starts getting warm and reduces the amount it's cooling the coolant.

As I described earlier, when we had the hot water heater out of the boat and I blanked off the send and return coolant lines for the heater, both engines came up to temperature at the same rate. Why? Because the starboard engine was no longer sending some of it's coolant off to have its temperature dropped way down by the still-cool hot water heater.

The logic seems pretty inescapable to me.



-- Edited by Marin on Saturday 20th of November 2010 12:07:16 PM
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Old 11-21-2010, 05:40 AM   #70
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RE: How Many Ford Lehmans are there?

Quote:
Marin wrote:

Our hot water heater is connected AFTER the engine's thermostat but it still acts like a second heat exchanger on the engine. Think about it. It doesn't make any difference where the coolant loop leaves and enters the engine relative to the thermostat. The fact is that coolant is sent off to circulate through this giant heat exchanger which cools it down until the hot water heater is up to temperature. The coolant coming back to the engine from the colder hot water heater has been cooled down, and this drops the temperature of the coolant it's mixing with in the engine. This is going to happen no matter where you take the coolant from or where you return it to relative to the engine's thermostat. As long as the hot water heater is part of the loop the coolant goes through, it's going to cool down the coolant it's mixed with back in the engine until the water in the water heater has warmed up enough to not drop the coolant temperature lower than the thermostat can deal with. Doesn't matter if you take it before the engine thermostat or after it.

Everybody I've talked to with a twin engine boat with the hot water heater attached to one engine has the same situation as we do. The engine with the hot water heater in its cooling loop takes longer to get to operating temperature than the one without the hot water heater in the loop.

It's no different than driving a car in cold weather. If it's cold out, the car takes longer to come up to temperature than when it's hot out. Why? Because the coolant is getting cooled a lot more by the radiator when the air is cold. It's got nothing to do with the thermostat, it's got every thing to do with how much heat is being taken out of the coolant by the radiator. Just like having an "extra" heat exchanger in the cooling loop of a boat engine, which is what the hot water heater is.

An extreme example in vehicles is when they're operated in very cold temperatures.* The cooling effect on the radiator is such that it overwhelms the thermostat's ability to regulate the engine's temperature and the only answer is to restrict the airflow through the radiator.* Hence the radiator covers you see on trucks up north in the winter, and the "window shade" radiator shield that was on older Volvos.* In the boat, that big, cold, hot water heater is like that real cold air hitting the radiator.* There's little the thermostat can do about it until the water in the hot water heater starts getting warm and reduces the amount it's cooling the coolant.

As I described earlier, when we had the hot water heater out of the boat and I blanked off the send and return coolant lines for the heater, both engines came up to temperature at the same rate. Why? Because the starboard engine was no longer sending some of it's coolant off to have its temperature dropped way down by the still-cool hot water heater.

The logic seems pretty inescapable to me.



-- Edited by Marin on Saturday 20th of November 2010 12:07:16 PM
Sorry the logic is flawed.

It does make a difference where the loop leaves the system.* If it didn't they wouldn't always have the by pass near the thermostat.* Every engine has it in or near the thermostat housing.

The thermostat is what closes the loop with in the engine.* On those cold days the engine block does heat a little slower but that is because it starts out colder and is a big heat sink in itself.* But the engine gets to temp long before your temp gauge reads it.* That's due to where the temp gauge is placed, somewhere near the top hose return from said radiator.* The radiator is kept out of the loop until the thermostat starts to open and then coolant is allowed to flow to the radiator at a controlled rate by the thermostat.* If the coolant is cooling the block to quickly the thermostat closes down and slows the flow until the coolant with in the block is at 180* or whatever the setting is for the thermostat being used.*

The reason the water in the radiator freezes is the air moving over the radiator cools the radiator below the freezing point of the liquid and no hot or warm coolant is being introduced to the radiator because the thermostat is closed.* The cardboard over the lower half of the radiator was used in*place of a higher temp thermostat or in some cases where the people didn't have any money no thermostat at all.* But if the thermostat was of the proper temp and the coolant was set to the low enough setting there was*no need for the blinds or cardboard.* If you don't move the car it happens less due to less air flow.* Folks with a garage didn't have as much trouble with this as cars parked outside.* The other trick was to park a car with the front up against a building so the wind didn't blow through the grill. *Part of that was due to the fact that the coolants were not set to a low enough freeze point.* Have you seen a blind on anything built since 1970?* Even the over the road trucks don't use the covers on the engines anymore.* The big trucks used them because of the different areas of the country they would be in over a short period of time.* They couldn't change everything every other day to fit the temp changes from Miami to NY in December.* Coolants didn't exist and electric cooling fans didn't either so it was a lot harder to control the temps in those days.* So big radiators were needed for the warm climates and they cooled to much in the cold climates.

The point is that the engine block*is*getting to temp long before the gauge says's it is.* That is the function of the thermostat.**

I may have*miss understood what Andy was asking.***

*
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Old 11-21-2010, 01:22 PM   #71
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How Many Ford Lehmans are there?

Quote:
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Have you seen a blind on anything built since 1970?* Even the over the road trucks don't use the covers on the engines anymore.

*
Don't know where you live but we see them on almost every semi we pass on I-5 in the winter up here, particularly the ones down here from BC.* And take a look at the TV series "Ice Road Truckers."* All the trucks in that show have radiator shields closed all the way up except for a little square in the middle.

I ran my "logic" past one of our diesel mechanics yesterday and he said, "Right on, that's the way it works.* Doesn't matter where the heater connections on the engine are, the water heater will slow the rate the engine comes up to temperature."* The coolant pickoffs on our FL-120s are out of the side of the block, by the way.* They are nowhwere near the thermostat.

Having said all that I am sure there are a lot of different ways things can be connected and controlled, and there may well be a way on some engines to set up hot water tank heating from the engine coolant that does not affect the speed at which the engine's coolant comes up to temperature.* I certainly agree that the temperature gauge in most diesel applications is reading the coolant temperature, not the combustion chamber temperature.* On an FL120, the coolant temperature sensor is tyically mounted in the coolant header tank, which is "after" the thermostat down below it.** Our boat is equipped with EGT gauges as well as standard engine temp gauges and when we come up to cruise power at the beginning of a run both engines come up to the same EGT reading together even though the coolant temperatures are still very different.* EGT is still not the same as combustion chamber temperature, but I think it's a more accurate indicator than coolant temperature.

But in all the applications similar to what we have--- and the owners of twins I've heard comment on their engine-hot water tank setup seem to have had the same setup we have--- the engine with the hot water tank in the coolant loop always trails the other engine in terms of the coolant temperature as indicated on the temp gauges at the helm station.

But none of this would seem to get Andy any closer to an answer since the engine that provides hot coolant to his hot water heater is apparantly getting up to the proper (coolant) operating temperature.* So that would seem to rule out a thermostat problem as being the source of his hot water heater problem since it appears to be operating corrrectly.* And regardless of how his boat's hot water heater is connected to the engine's coolant system, the fact that it's worked fine until now would indicate the problem is not in the way it's hooked up but is due to some change that's occurred in the coolant loop itself.




-- Edited by Marin on Sunday 21st of November 2010 05:53:25 PM
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Old 11-21-2010, 06:39 PM   #72
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RE: How Many Ford Lehmans are there?

Is the lack of heat to the hot water tank a recent problem or has it been there all along and you have just decided to tackle it now.

If the engine is indeed getting up to temp and you are running long enough that the tank should be heating then take a look at the supply hose. What size is it. If it is too small then not enough water is pumped from the engine to the tank to heat in a reasonable time. At a minimum it should be 5/8" id and better would be 3/4". I noticed a big change in heatup time, when years ago I went from 3/4 hose to 5/8. I used Aeroquip FC300, massive overkill. The cost difference between the two sizes was enough that I cheaped out.

You might also double check where your connections are made. Maybe there is not enough pressure difference so the flow is not very high. See if you can check another boat that works well with your engine or the mfgr. to ensure the best connection points. Frequently the supply is taken from near the coolant pump (highest pressure) and returned somewhere on the block or head (low pressure)

If you are making changes install shut off valves at the engine so if you ever lose a hose you can isolate the tank. You may lose coolant but at least you will be able to top off and carry on untill you can efffect repairs.
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Old 11-23-2010, 03:19 PM   #73
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RE: How Many Ford Lehmans are there?

I am looking into this further and will report back when the problem has been found.
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