Yanmar 3gm Runs Too Cool

[riptide]

Re my earlier thread about noisy yanmar 3gm - removed water neck and surprise - thermostat was there! found 3 other t/stats on boat and tried 2 of them.the motor still wont run over 120 deg. read about some stats working in rev. ie:normally open - but that doesn't seem to be the case here.I was unable to see any deg. markings on any of the stats. was wondering if they make diff. ones like for cars? I live in tenn. and would like any info on who will sell yanmar parts to tenn-seems to be a territorial issue.Any other Ideas on what to look for would be appr. oh by the way the engine is raw water cooled. I really think my noise and smoking problems are related to engine running too cool as when I purchased boat I ran 50 mi. down a river to haul out and after about 45 min. engine quieted down and quit smoking although temp. was still low (around 130 deg.) Am going to take my temp gun to boat this weekend to try to make sure gauge is correct and check diff. places on motor. any ideas would be app. thanks

[Solitude]

My 1gm10 is raw water cooled. It is noisy on startup as well. You can check if a t -stat works by putting it in a pan of warm water and seeing if it opens and at what temp, as you warm it up. If they are open in cold water there garbage. How warm does it get to the touch. I can rest my hand on the valve cover without burning it.

Were the other t-stats new? Some people like to replace parts and keep the old ones lying around. Maybe you have a bunch of old t-stats. How many hours on the motor. Do you have a manual? I have a link to one

[riptide]

all the stats. were used. they all seemed to opreate freely.I put the one with stiffest spring in.I don't seem to be able to find anyone that will sell yanmar parts in tenn.so I'm having aproblem getting a new one. the eng does run cool you can touch valve cover ect.Does yanmar sell diff. temprature stats? I dont have manual and would appr. link.thanks

[Solitude]

Im in Canada so you wouldn't want to buy one here$$$.

YES Yanmar is teritorial! I wanted to buy an engine stopcable at my local marina. They had a Yanmar sign on the door. He wanted 65$ Online US 22$. Went to the local Yanmar dealer 40$. I guess my local guy had to buy from the dealer and added 25$. Live and learn.

Back to your problem I would buy a brand new one. But I was once told that I should be able to hold my hand on the valve cover (while running watch your sleeves) without it getting too hot.

The tstats should be closed when cool. If they were open they are garbage.

Here is a online place that said they would ship to me in Canada.
sales@yanmarpartsonline.com

Yanmar Manual

Cascade Engine Center | Diesel Engines | Yanmar Manuals

[Highlander40]

My Yanmars are bigger, 6LY-STE 420 hp but still a mechanical engine.
They run at 75 deg C or 167 def F but they smoke when cold. The fuel system is calibrated for running temperature. This is the big thing about the new electronic engines, they start up with out smoke.
Once you get the thermostat straightened out, try a cetane improver or add 2 to 5 % biodiesel. That helps. I use both.

[Badsanta]

It should run about 180. Check with your temp gun that may tell all. For parts I use Lake Michigan and Great Lakes Sailing Information - Torresen Marine, Inc. - Muskegon, Michigan They do Virgina and your next door. The site said they do 20 east coast states but did not list them. Also try Mac Boring, Both have worked well for me

[shakey doug]

Yes, There are two thermos one for salt water cooled engines this is a 52c unit or low temp this has to be used to stop various minerals causing water passage restrictions--over heating. Fresh water cooled engines are fitted with a 82c unit,a freshwater cooled engine will run --smoother---quieter--cleaner--longer ----than a saltwater cooled unit.

[Tropic Cat]

If a closed system with fresh water and a heat exchanger is used, 180 degree thermostat is correct. However, if he's raw water cooled then a 180 degree thermostat would destroy the engine. Raw water requires a 120 degree thermostat.

[Highlander40]

There you go.

[Badsanta]

Yes, you have the 120 and 180 correct. I miss read the engine and was thinking of the 3gm30f. My bad.

[riptide]

Interesting! I wasn't aware of the diff. between raw fresh water cooled ,thanks for m aking me aware. So if my engine is running 120 it's probably running at the proper temp. I wish I could run warmer it sure is quieter-but I guess i'm looking at a heat exchanger.Any ideas on where to get a kit? thanks again all!

[Solitude]

I'm not sure how many hours on the engine but your Yanmar is made to run with raw water cooling. You need quite a few peices to put a heat exchanger in including another rawwater pump driven by a second pully etc. Of course it can be done but raw water will not kill your engine.

Yes many more Yanmars have freshwater cooling in that size.

One tip with raw water cooling is to put a T in the intake line and flush it out after running it with a salt removing product.

[shakey doug]

Yes, there are kits most good agents can source these. Unless you intend to run a hot water supply system or need to spend some money the real benefits are not to be had.There are old px series yanmars getting about that have had raw water cooling for 50+years and still going strong good owners regular services -Check ANODES every 3rd full moon .If sysem requires cleaning fill with vinager leave 24hr and flush, beware of some strong acids as they can cause problems.