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ottow · 15-01-2018, 11:00

I'd suggest check the hoses everywhere also. Below is a picture of the inlet hose from my VP 2002 after I had cut it in half where there was a slight bulge on the outside.
The blockage was perhaps 30-40%. First time I saw a hose delaminate...

jr_spyder · 16-01-2018, 14:42

Totally stumped.

Here’s where I am, including some feedback on above input:

Raw water side:
1. Through hull is clear from below.
2. Strainer is clear
3. water pump">Raw water pump was new two years ago. Seems like new.
4. Impeller looked great but replaced anyway.
5. Flow through heat exchangers is unblocked. Removed main exchanger today and water from dock hose ran through both raw and fresh sides very easily at no noticeable decrease in pressure. Nonetheless I have the exchanger at a shop for further testing.
6. Mixing elbow is fine! We really thought this was a high probability but no issues. There’s a large open passage for the raw water to run through before it joins the exhaust at the bottom of the elbow. Looks impossible to block. That said, I need a new one. The flange where it connects to the exhaust manifold is half eaten away and was leaking gases. This fact prevents me from putting everything back together right away.
7. All fittings, nipples, hoses, etc. are clear and unobstructed on both raw and coolant side.

Now to the coolant side.
8. Thermostat removed and checks ok, but will put in new one.
9. Took apart water pump on front of engine. Spins freely and smoothly. Impeller like new.
10. Removed housing on front of block where water from pump flows into block, and returns to thermostat housing. All passages are perfectly clear looking into block. Impressively so.
11. Temperature switch (for high limit) changed because I had one.
12. Temperature sender still suspect. I didn’t think I had one so didn’t change it early for that easy check. On deep searching for other parts I found one, but miss labeled, in my kit. Can’t check it until everything’s fully back together of course. That said I did use an ir thermometer on the top of the tstat housing and it compares well to the gauge. So that should indicate the sender isn’t a problem, but it could be flaky.
13. Can’t test quality of coolant but it’s clear, but showing some age. Hard to imagine it’s a problem. Will replace after a few flushes.

Not done: I haven’t measured raw water flow, and can’t until it’s all back together. It also will take at least two, maybe three people (helm, bucket, timer) to do it so I have to plan carefully. It’s a lot of water - about a gallon every 4 seconds. Gotta act fast.

Running out of options!

**boatman61** · 16-01-2018, 15:02

Okay.. so one other possibility.. follow your exhaust hose from where it leaves the engine and it should come to a white rectangular collector which are sometimes known to fail.. black holed on the name of them.. but they have a non return thingy in them.. if your intake and ejection don't match up that could well be the reason.
Ohh..!!! and be prepared for the possibility of the main exhaust hose walls possibly collapsing..
I got the hell scared out off me on my Westerly Longbow back in the 90's.. motoring along then a loud explosion at the stern.. turned out the big baffle in the system that kept noise down and stopped backflow up the outlet had collapsed internally and the build up of pressure caused it to explode, result.. unplanned stop in Villamoura for 3 days.

NYSail · 16-01-2018, 15:35

Regarding the coolant..... don’t judge by what it looks like. The funk sits low and that pretty green breaks down. Flush without thermostat and fill with new orange stuff. And with mixing elbow..... water side may be fine but if exhaust side is blocked you have back pressure and retained heat. New one can’t hurt.....
You’re almost there......
Good luck!

sailorboy1 · 16-01-2018, 15:45

Quote:

Originally Posted by jr_spyder

Running out of options!

As I remember the start of this you are chasing a 5 degree increase on the panel gage. How do you know it is reading right and that your engine isn't running in the specified temprange? I've had to replace all the panel gages the past 7 years.

jr_spyder · 16-01-2018, 17:22

Sailorboy - it has run up to 210° which is more cause for alarm. Also I have used an ir thermometer on the top of the thermostat housing and it read within a few degrees of the gauge. I only did this once tho so it deserves more observation to be sure, but that would indicate it’s not the gauge. It also doesn’t rule it out yet.

jimbunyard · 17-01-2018, 22:30

Quote:

Originally Posted by jr_spyder

Totally stumped.

Here’s where I am, including some feedback on above input:

Raw water side:
1. Through hull is clear from below.
2. Strainer is clear
3. Raw water pump was new two years ago. Seems like new.
4. Impeller looked great but replaced anyway.
5. Flow through heat exchangers is unblocked. Removed main exchanger today and water from dock hose ran through both raw and fresh sides very easily at no noticeable decrease in pressure. Nonetheless I have the exchanger at a shop for further testing.
6. Mixing elbow is fine! We really thought this was a high probability but no issues. There’s a large open passage for the raw water to run through before it joins the exhaust at the bottom of the elbow. Looks impossible to block. That said, I need a new one. The flange where it connects to the exhaust manifold is half eaten away and was leaking gases. This fact prevents me from putting everything back together right away.
7. All fittings, nipples, hoses, etc. are clear and unobstructed on both raw and coolant side.

Now to the coolant side.
8. Thermostat removed and checks ok, but will put in new one.
9. Took apart water pump on front of engine. Spins freely and smoothly. Impeller like new.
10. Removed housing on front of block where water from pump flows into block, and returns to thermostat housing. All passages are perfectly clear looking into block. Impressively so.
11. Temperature switch (for high limit) changed because I had one.
12. Temperature sender still suspect. I didn’t think I had one so didn’t change it early for that easy check. On deep searching for other parts I found one, but miss labeled, in my kit. Can’t check it until everything’s fully back together of course. That said I did use an ir thermometer on the top of the tstat housing and it compares well to the gauge. So that should indicate the sender isn’t a problem, but it could be flaky.
13. Can’t test quality of coolant but it’s clear, but showing some age. Hard to imagine it’s a problem. Will replace after a few flushes.

Not done: I haven’t measured raw water flow, and can’t until it’s all back together. It also will take at least two, maybe three people (helm, bucket, timer) to do it so I have to plan carefully. It’s a lot of water - about a gallon every 4 seconds. Gotta act fast.

Running out of options!

Running out of options?...not at all.

From this picture of your (likely) elbow (pleasantly not overpriced, even from WB)

I agree that it looks 'impossible to clog". That being said, it could still flow and either not flow enough or be corroded enough to not efficiently transfer heat, which could, as before, over time eventually cause a build up of heat in the system, especially if the system is running at the upper end of the envelope.

Since you have a new elbow on the way, if everything else checks out OK (as it appears to have), install the new parts, and give it a test. You may be surprised to find you've fixed your problem.

There are of course other things you can do.

If the engine has an automotive type tstat, put in one rated for a lower temperature (but not too much lower).

As previously suggested, run straight water with a corrosion inhibitor/lubricant. You do not need antifreeze/antiboil in your circumstance; the substantially better heat transfer characteristics of pure water could easily push you down into an acceptable range.

Is the diameter of your exhaust system the same throughout? In other words, at any point is the diameter of any particular section smaller than that of the outlet of the exhaust elbow?

This is not the end of the world, but with systems that are on the edge, a change in the ambient (air and water) environmental temps could push the operating temperature over that edge. If the hypothesized 'restriction' is enough, exhaust pressure could slow down the flow of water enough to eventually cause an overheat, especially when running under heavy load.
In this case, a bypass for raw water can be arranged, valved for modulation if necessary, to allow enough cooling water to flow through the heat exchanger, whilst still providing enough water to cool the exhaust stream.

Realistically, though the engine seems to run well, the slight overheating could be a sign of an incipient failure, possibly a head gasket or similar. When you get it all back together, start the engine and watch the temperatures with your IR thermometer at each manifold exhaust flange where it meets the exhaust outlet on the head. The temps should rise at pretty much the same rate. Once the engine is at full operating temp the readings at the individual outlet/inlets should be very similar. If not this could indicate a compression or injection problem for the variant cylinder.

And finally, from your initial post

"In the short easy mile the temp dropped to 190 but seemed to bump up and down 5° like I’ve never seen before."

might indicate air trapped in the freshwater side. Make double-sure that this is not the case...

james247 · 18-01-2018, 02:41

Quote:

Originally Posted by jr_spyder

My engine is starting to show hotter than usual temps. I usually cruise at 180° in cool New England waters which crept up to 185°F in tropics, but I’ve seen 190° lately, and this morning 200. I was fighting into a strong wind and the engine was working harder than usual. I slowed down and turned out of the wind into a quiet anchorage. In the short easy mile the temp dropped to 190 but seemed to bump up and down 5° like I’ve never seen before.

Once the engine cooled I did a bunch of checks.

- Strainer clear
- opened impeller housing. Impeller perfect, but replaced it anyway
- opened heat exchanger. Very clean inside with open tubes
- water flow out of exhaust pipe is robust. Doesn’t seem a problem.
- fan belt on coolant pump fine
- coolant level correct

So overall the raw water side seems fine. That makes me suspicious of the engine thermostat, which is far more difficult to access, naturally. I do have a spare on board, but not a spare gasket (doh!).

Before I do thermostat job I’m wondering if there is other advice here.

Also, what’s the likelihood I can take the thermostat housing apart and reuse the old gasket? I have some gasket sealer goop. I’ve seen both extremes of gaskets being completely reusable to completely destroyed. I really don’t want to risk taking it apart in a remote place and not being able to seal it back up.

The engine is a Westerbeke 82B with unknown total hours but 1600 hrs since major overhaul according to previous owner. Runs fantastically well. Maintained obsessively by me, but I might be missing something.

Thanks,

JR

New England water temperatures are very low. Tropical and Equatorial waters are hot. The water temperature in shallow water can approach 36 to 38c. I removed my thermostat all together in such waters. There maybe a thermostat for warm waters. Starting in warmers doesn't require glo plugs or the like.

B-Baysailer · 18-01-2018, 18:13

Check the cam in the raw water pump a worn cam can reduce the pump out put by up to 50%

boatpoker · 19-01-2018, 11:21

A raw water flow detector/alarm is a huge advantage over an engine overheat alarm as it will sound the instant raw water stops flowing. By the time an overheat alarm sounds it's likely that at least the impeller is toast.

I've had a flow detector between my strainer and raw water pump on all my boats and would not be without one.

jr_spyder · 24-01-2018, 08:27

Thanks again for all input. Sorry I've been silent, flew back to the States as my wife had a medical issue but doing better now.

Westerbeke delivery just got here and I have a shiny new exhaust elbow, gaskets, temp sender and thermostat.. Not sure yet when I'll get back to the boat. I'll put everything back together, flush the engine and leave it full of plain water at first and start testing again.

As to comments above:

Cam in water pump was new 2 years and approx 80 engine hours ago. Worth a check, but not likely a problem. Overall I need to test the actual water flow to be satisfied all is well. I have a three way valve at home that I'm going to bring back to the boat, temporarily put in the raw water line just before the exhaust elbow and see if flow meets spec (14 gph at 3600 rpm). With the valve I can simply divert flow into a bucket in the engine room (funniest name around!) and get a good approximation of flow. If all is well here I have other issues either more down stream or on the coolant side.

Jim - thanks for very thorough thoughts and ideas. Good things to keep checking. Hoping new elbow just makes this problem go away. Incidentally, looking at new elbow now I can imagine how a build up corrosion could happen inside and restrict raw water flow.

Jim and Boatman - downstream of my elbow I do have a trap device that I think of as a muffler. All pipes stay the same size all the way (2" id). The exhaust and raw water flow down into a vertical cylinder which is about 16" deep and 10" round. Exhaust/water exits going straight up to a high u-bend well above the waterline - obviously this is here to prevent back flow of water from the stern. There is no sign of any sort of mechanical check-valve to stop back flow. After the u-bend the hose drops down to bilge level and works its way to the stern (my boat is a center cockpit).

I suppose the "muffler" could be full of grit and causing back pressure. I'll take a look inside through the hose flanges.

If after reassembly I still have a high temp the first thing I'll do is change the temp sender. I want to isolate that as a question. If I'm still in trouble I'll test the water flow, and keep going from there.

JR

jr_spyder · 24-01-2018, 08:51

Boatpoker - love the idea of the flow alarm. Been doing some searching but can't find quite the right thing. Tell us more about what you have please.

Sea Life · 24-01-2018, 08:56

JR,

Given the size of your boat, and my assumption of hp, that flow rate sounds very low. Heat rejection varies etc. etc. but for comparison NL gen 1800rpm 3cyl, ~10hp needs 300gph or 5gpm.

Cheechako · 24-01-2018, 08:59

Quote:

Originally Posted by jr_spyder

Boatpoker - love the idea of the flow alarm. Been doing some searching but can't find quite the right thing. Tell us more about what you have please.

What I've done before is buy a "snap disc" thermostat from Graingers. They come in various temperatures. I've seen adjustable ones too. I think I used a 170 degree one. I just clamped it to the exhaust elbow with a hose clamp. When it reaches the temp it closes the switch activating a buzzer or light. Use a 12 volt buzzer with it.
https://www.mouser.com/ds/2/459/Cat_06_pg0090-607.pdf