Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 08-10-2019, 00:37   #16
Registered User

Join Date: Aug 2010
Location: sydney, australia
Boat: 38 roberts ketch
Posts: 1,246
Images: 3
Re: Does anyone replace thermostat...

yeah, 2qm20, gave the manifold a pretty thorough massage with a dirty big screwdriver to encourage the white gunk to go on its way. Mine doesnt have a drain tap on the manifold so no probs there. Didnt block the bypass, just removed the thermostat and re-gasketed the housing, my intention being to encourage constant raw water flow through both engine and manifold at all times - same dirty big screwdriver is employed when lower anode nut is removed from front eng. water input area as this has concreted up in the past with anode residue. There doesnt appear to be much difference in the heat up rate with or without the thermostat in place, I like the original design idea of a quick heatup bypass but I think I've heard a tiny bit of disrespect from other quarters for the...sincerity and dilligence of the manufacturer which leaves me unrepentant in varying their design to suit my own prejudices
__________________

charliehows is online now   Reply With Quote
Old 08-10-2019, 00:45   #17
Registered User

Join Date: Aug 2010
Location: sydney, australia
Boat: 38 roberts ketch
Posts: 1,246
Images: 3
Re: Does anyone replace thermostat...

dammit - now you've got me thinking about it, I might block the bypass to force all the flow from eng. thru. manifold to exit...I've been puzzling over whether there is much water passing through the bloody pipe from the eng across to the manifold...I thought it best to leave well enough alone in just taking out the thermostat...maybe I'll give a try to blocking the bypass...let you know the results in a few weeks. Cheers.
__________________

charliehows is online now   Reply With Quote
Old 08-10-2019, 14:14   #18
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 1,213
Re: Does anyone replace thermostat...

Quote:
Originally Posted by charliehows View Post
dammit - now you've got me thinking about it, I might block the bypass to force all the flow from eng. thru. manifold to exit...I've been puzzling over whether there is much water passing through the bloody pipe from the eng across to the manifold...I thought it best to leave well enough alone in just taking out the thermostat...maybe I'll give a try to blocking the bypass...let you know the results in a few weeks. Cheers.
I'm interested as to what pans out in this experiment. If you have an infrared thermometer could you check the head temp & the manifold temp before you make the changes? Several measurements as it warming if possible. No worries if it's too much of a PITA.
Sorry for the thread drift but curiosity killed the cat.
Compass790 is offline   Reply With Quote
Old 08-10-2019, 18:01   #19
Registered User

Join Date: Jan 2008
Location: SF Bay Area (Boat in La Paz)
Boat: Valiant V40
Posts: 606
Re: Does anyone replace thermostat...

No real opinion on the lifetime of a T-stat, but ...

It is a lot easier (and safer) to change out a T-stat on a cool engine (with a cold beer nearby) than on a hot engine (under duress.)
jamhass is offline   Reply With Quote
Old 08-10-2019, 18:23   #20
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 9,671
Re: Does anyone replace thermostat...

Quote:
Originally Posted by jamhass View Post
No real opinion on the lifetime of a T-stat, but ...

It is a lot easier (and safer) to change out a T-stat on a cool engine (with a cold beer nearby) than on a hot engine (under duress.)
This is so so true

It highlights the fact that you can choose when/where to do scheduled maintenance but the engine decides when/where to do unscheduled maintenance - I know which I prefer!
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is online now   Reply With Quote
Old 09-10-2019, 13:59   #21
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 1,213
Re: Does anyone replace thermostat...

Quote:
Originally Posted by charliehows View Post
yeah, 2qm20, gave the manifold a pretty thorough massage with a dirty big screwdriver to encourage the white gunk to go on its way. Mine doesnt have a drain tap on the manifold so no probs there. Didnt block the bypass, just removed the thermostat and re-gasketed the housing, my intention being to encourage constant raw water flow through both engine and manifold at all times - same dirty big screwdriver is employed when lower anode nut is removed from front eng. water input area as this has concreted up in the past with anode residue. There doesnt appear to be much difference in the heat up rate with or without the thermostat in place, I like the original design idea of a quick heatup bypass but I think I've heard a tiny bit of disrespect from other quarters for the...sincerity and dilligence of the manufacturer which leaves me unrepentant in varying their design to suit my own prejudices
Thinking about your experiences it seems it wouldn't be that critical having a thermostat in your case any way as with Sydney water say 20oC & thermostat fully open at 52oC with the temp difference being only 32o it's not comparable with a heat exchanger equipped engine where the temp difference would be around 60oC.
More thinking ( dangerous perhaps lol) leads me to believe the thermostat is on the exhaust manifold as that probably heats up faster than the head & block on the large 2QM20.
I'd imagine your 2QM20 would take an age to heat up unless it was put under load anyway.
Whilst it would seem to be always preferable to have a thermostat rather than not I can see, in your case, the problems it causes make it not worth it.
Have you had to replace the exhaust manifold in your ownership?
Compass790 is offline   Reply With Quote
Old 09-10-2019, 14:45   #22
Registered User

Join Date: Aug 2010
Location: sydney, australia
Boat: 38 roberts ketch
Posts: 1,246
Images: 3
Re: Does anyone replace thermostat...

Has original manifold. t.stat on manifold. My attitude to the heating up of the engine - irrelevant, but gentle use of engine on the assumption that its mostly running a bit cold. Give it a bit of a blowout when I know its been running long enough to be up to temp. Current plan - incorporate a tap into by-pass hose. My only concern in diverting all flow through eng. + manifold is pressure.
as they say on TV; 'dont try this at home, kids' but if you have a 40 yr old 2qm20 this may be of interest to you...
charliehows is online now   Reply With Quote
Old 09-10-2019, 17:19   #23
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 9,671
Re: Does anyone replace thermostat...

Quote:
Originally Posted by charliehows View Post
Has original manifold. t.stat on manifold. My attitude to the heating up of the engine - irrelevant, but gentle use of engine on the assumption that its mostly running a bit cold. Give it a bit of a blowout when I know its been running long enough to be up to temp. Current plan - incorporate a tap into by-pass hose. My only concern in diverting all flow through eng. + manifold is pressure.
as they say on TV; 'dont try this at home, kids' but if you have a 40 yr old 2qm20 this may be of interest to you...
Hmm... I don't see anything to worry about - assuming the waterways in the manifold are mainly clear of crud. There is no substantial pressure in the raw water cooling circuit, it is essentially open to the atmosphere or at least open to the back pressure in the exhaust system.

When the thermostat is fitted and the thermostat is in the cold position, all cooling water passes directly from the pump to the exhaust injection point via the bypass hose and none though the block/head/manifold.

When the thermostat is fully hot, all cooling water passes though the block/head/manifold and none though the bypass hose.

Your tap (when closed) in the bypass hoses is just replicating a fully hot thermostat. IMO, the tap (or any permanent blockage) is essential if you remove the thermostat.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is online now   Reply With Quote
Old 09-10-2019, 17:52   #24
Registered User

Join Date: Jun 2019
Location: Bay of Islands New Zealand
Boat: Morgan 44 CC
Posts: 277
Re: Does anyone replace thermostat...

Quote:
Originally Posted by charliehows View Post
yep, in theory. try telling that to a 40 year old engine still running like a sewing machine.
The function of the thermostat is to keep engine temperature up. The reason is two-fold - firstly hotter engines experience less wear and secondly hotter engines use (infinitesimally) less fuel. As an non-marine example, I have a V12 BMW that runs a higher pressure cooling system and the normal operating temperature is 108 degrees C. Because the car is inherently thirsty, the high temp is ostensibly to reduce fuel consumption. But honestly, I put a custom thermostat (85 degrees) in and have noticed no difference.

But engine wear? Well, I donít expect the engine to last more than 600,000kms anyhow A Yanmar would probably also not notice any difference.

To come back on topic, I canít recall ever replacing a thermostat that wasnít faulty. Thermostats always fail to open when faulty - my fallback then is to remove it and get a new one when I next can. Itís really no biggie.
CassidyNZ is offline   Reply With Quote
Old 09-10-2019, 17:59   #25
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 26,911
Re: Does anyone replace thermostat...

If it wasnít necessary then itís not likely that Yanmar would have wasted the money to install one.
a64pilot is online now   Reply With Quote
Old 09-10-2019, 18:50   #26
Registered User

Join Date: Aug 2015
Location: Marina del Rey
Boat: Hunter 31
Posts: 863
Re: Does anyone replace thermostat...

I occasionally test mine by forgetting to open the raw water seasick. The warning starts with a hissing sound from the alarm before the high pitched alarm kicks in. I would not recommend this method though .
Pizzazz is online now   Reply With Quote
Old 09-10-2019, 18:54   #27
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 1,213
Re: Does anyone replace thermostat...

Quote:
Originally Posted by Pizzazz View Post
I occasionally test mine by forgetting to open the raw water seasick. The warning starts with a hissing sound from the alarm before the high pitched alarm kicks in. I would not recommend this method though .
You are not the only one to use this method lol
Compass790 is offline   Reply With Quote
Old 10-10-2019, 14:06   #28
Registered User

Join Date: Jun 2019
Location: Bay of Islands New Zealand
Boat: Morgan 44 CC
Posts: 277
Re: Does anyone replace thermostat...

Quote:
Originally Posted by a64pilot View Post
If it wasn’t necessary then it’s not likely that Yanmar would have wasted the money to install one.
Along with every other engine manufacturer on the planet Astonishing how often methods proven over a century of development are wiped off the table by folks who think there’s a better way.
CassidyNZ is offline   Reply With Quote
Old 10-10-2019, 14:27   #29
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 1,213
Re: Does anyone replace thermostat...

Quote:
Originally Posted by CassidyNZ View Post
Along with every other engine manufacturer on the planet Astonishing how often methods proven over a century of development are wiped off the table by folks who think thereís a better way.
Actually progress/improvements are only made by people who think there is a better way not those that blindly follow what has gone before.
Yes plenty of mistakes are made thinking you have a better way but also sometimes there is a better way.
Not that I'm arguing it's better not to have a thermostat!
However, in charliehows case it causes problems.
It's hard to have blind faith in engine manufacturers when you come across obvious flaws in their design.
What I find astonishing is that people think that engine manufacturers are infallible. YMMV
Compass790 is offline   Reply With Quote
Old 10-10-2019, 16:42   #30
Registered User

Join Date: Mar 2019
Posts: 240
Re: Does anyone replace thermostat...

What exactly is the failure mode on a bimetal strip connected to a spring and plunger? I'm sure one has failed somewhere sometime but it has to be vanishingly unlikely. Far more likely that it's jammed with crud, which wouldn't require replacement, and far far more likely as several have pointed out that the hoses need to be preventively replaced. Proactively replacing a thermostat annually as it sounds like one engine manufacturer recommends is just lunacy!
__________________

redneckrob is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Does one of these replace flares Navicula Health, Safety & Related Gear 3 19-12-2018 16:48
400: Getting to back of Freezer to replace thermostat Whomda Lagoon Catamarans 2 29-01-2018 21:29
Which Electric Motor Does Harken Use? I need to replace one solecollector Deck hardware: Rigging, Sails & Hoisting 2 28-10-2017 09:47
Lines - To replace, or not to replace? TooCoys General Sailing Forum 31 25-04-2017 13:32
Thermostat and thermostat housing pbmaise Engines and Propulsion Systems 22 13-01-2017 14:30

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 16:33.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.