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Discussion Starter · #161 ·
I do actually. Judging by the lack of witness marks on the fasteners, none of it was ever touched before I got it. And when I took it appart, I did take note of the little alignment mark on the fuel rack; it was right where it's supposed to be according to the service manual. That's where I put it back to. The amount that I adjusted it yesterday coincides with how much Iadjusted it before, and since I marked it before moving it, it ended up right back where it was anyway. So it ought to be pretty darn close. No better than the dealer could do at least. Not as good as a proper injection shop would do, but I think that's ok, it should be good now. I noticed a distinct difference in the amount of smoke when going up a steep hill with the MCS going...or rather lack thereof.

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(y)

I think I've mentioned it, a free flowing exhaust in a diesel does wonders for eliminating heat on these older engines. Mufflers were a compromise. Nobody likes hearing the dull blat of a diesel in their ears when working, so the factory installed a muffler. But, out of necessity due to space restrictions, they installed a small restrictive muffler. It quiets the exhaust though because that was more important than getting the best running engine. Because they did have noise laws back then to contend with.

Sorry, preaching to the choir again.
 

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Discussion Starter · #163 ·
More reasons why I added sound deadening to the hood and side panels, which did work! I always wear my ear muffs when running it around for more than 10 minutes too :)
 
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I wasn't paying enough attention before but if you're losing coolant, then check if the precombustion chambers have access to the coolant jacket - if so, you may have a leaking or cracked chamber, and that could also explain the high coolant temps. This would be less likely with a leaking liner seal and you'd also probably see a lot of coolant in the oil. Do you see any coolant there?. See this problem occasionally on old Cats. Chambers and seals are "usually" not expensive but I don't know Yanmar prices
 

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Another data point for you.

Yesterday I did my final mow of the year (Southern Ohio). It was 50 degrees outside. I mowed for 1.5 hours. Temperature never got over 152 (At the thermostat).

-Andy
 

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Discussion Starter · #166 ·
Andy,

How did you measure the temp, and you must have only had a mower going? I'm measuring with a K-type thermocouple in a bolt where the temp switch normally goes. 160F is when the thermostat
Just cracks open, so you were under thermostat control.

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Measuring with digital gauge in place of over temp sensor.

Thermostat never opened I’m sure.


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Discussion Starter · #168 ·
Happy Springtime Everyone! Hope everyone is doing well considering the state of the universe these days.

As I dislike a thread with no resolution, I'd like to continue on this journey until a solution is found.

Fully instrumented with thermocouples, ACDelco radiator cap with 2 gaskets (for a proper recovery bottle system) tested to 15psi. I mowed today for the first time this year. It was 79F outside.

  • I started up and let it idle for 10 minutes, you can see that the radiator in temp (RadIn) would have flatlined at about 160F, the temp at which the thermostat just begins to open.
  • 10 minutes - I started mowing (no MCS today)
  • 13 minutes - The dip in the curve was because I bounced up the seat and PTO safety shut down. I decided to stop and check instrumentation to see it was still reading and recording before continuing on.
  • 20 minutes - I stopped briefly to make sure my instrumentation was still recording, you can see the little heel in the curves where this occurred.
  • 30 minutes - I stopped again to check the instrumentation (as well as coolant temp specifically since I don't have an idiot light right now)
  • 39 minutes - I finished mowing, then parked in my garage at half idle for about 3 minutes allowing the engine to cool some before I shut the engine off.
  • 42 minutes - I shut the engine off and opened the hood.
  • 53 minutes - I stated the engine back up again, idled a few seconds, then max RPM a few more, then stopped. Just to see what would happen.
No coolant in the recovery bottle, or in my glass sight tube at the top of the radiator. Also, worth noting that I have the radiator packed full of coolant right to the top. No expansion volume. This is to force higher pressure and push coolant into the recovery bottle. I want my sight glass to be full of coolant so I can see if gas is created inside the radiator. If it is, that means there's a head gasket leak (or air leaking in to the cooling system).
  • Transmission/hydro (Trans) did not stabilize after 40 minute engine on time (almost 176F). The book says not to exceed 200F continuous operating temperature for reference.
  • Engine oil (DipStick) was almost stabilized at 248F
  • RadIn stabilized at 203F (and we know the light comes on at 225F)
  • RadOut at 195F
  • Grill and Fan air discharge are the air into and out of the radiator.
Enjoy.
 

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Discussion Starter · #170 ·
Thanks Tom! I could go the easy way and cut some speed holes in the hood to increase airflow, it definitely won't overheat then. But I really want to figure this out, as I suspect there truly is/was a problem. The most likely culprit is some kind of head gasket leak only at high engine load. Also, nerd cooling engineer want to reverse engineer all the things...
 

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Welp! Way over my head...Ima lick my finger and test the air currents kinda scientist. My solutions are almost always to throw money at it. That scientific process stuff is for those with maximum patience. Excellent work though!

But I'm curious still... at 23-25 minutes the intake air and cooled air dropped...the cooled air stayed down but the intake side went back up? Why did the radiator start cooling better??
 

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Also, nerd cooling engineer want to reverse engineer all the things...
Oh I can relate! It's not that we are smarter than the designers, we just may have different idea's on how to get job done. Designers had constraints, like cost and production feasability, we have neither of those, we are free to think outside the box and let the creative juices flow.
 

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Aaron, VERY impressive and thorough data and one helluva chart recorder with 6 inputs!

Looking through the chart, I see an issue! Just prior to the end of your mowing, I see the radIn & radOut starting to flat line, stabilize, but I see oil temp still at a constant rate of increase during the same time period. That tells me the radiator is working as fine as it possibly can but the coolant is not absorbing all of the heat the engine is producing. Somewhere along the line, Yanmar Engineers drop the ball! MY thoughts are coolant is passing too quickly through the engine and doesn't have enough time to absorb the heat. This is also indicated at your engine restart. You shut down and RadIn was 203ºF and when restarted, temp spiked to 208ºF. I see this at coolant sitting in engine absorbing engine heat while engine is not running.

MY issue is oil temp. There will be a point somewhere that this will flat line, but your chart shows a straight line of oil temp increasing, so where is this point? Once again, engine is producing heat, oil temp increases, coolant does not absorb the heat the engine produces, and radiator has a constant temp difference between temp in & temp out! where will oil temp flatline...260ºF, 350ºF or ???

Another consideration... maybe! I'm not familiar with your tilt MCS. Is this driven by the deck or a separate blower motor? If deck driven, this would require more work from the engine and more heat produced.

Something that you may want to try, although your quality of cut will suffer, is mow at 1/2-3/4 throttle. Possibly (??) this will slow coolant flow enough for it to absorb more engine heat.

Excellent test with results that are all in line with each other and make sense!. Will you be performing other tests? Bob
 
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Bob has a good point on the oil temp. Oil temp at 248 is entering the danger zone. The diesels I work on, mostly Int have oil coolers. Oil and coolant run stabilize at about the same temp. Warning lights and shutdown at 230, i think it is.

As a reference, last month I had my 332 rad recored. It started leaking steady from the top tank. It never indicated any signs of over heating since i bought it last July.
Heres the head scratching thing. When i took it apart, the rad was partially blocked on the air in side. The rad shop then informed me several of the core tubes were blocked also. Then i found there was NO t stat in the pump outlet. Also found the rad cap to be weak.
I had run the tractor in 90 plus summer heat, it should have boiled over, but didnt.

Everything is back together with all new JD parts now. I've only used it a little so far. I'm trying to get a deck that's in better condition, so I'm using the 318 to mow with.

With all that said, it's odd yours is over heating.
Mine had 4 strikes against it.
 

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Discussion Starter · #175 ·
OK, I re uploaded the image. I had forgot to convert seconds to minutes on the bottom. Should be a little easier to look at now.

Randy - I think you're talking about the part at the end where blue and green separate? That'd be when I shut the engine off, so coolant stopped flowing. The slow decrease in temps of both before that is while I had it sitting idling to cool before shut down. Green spikes back up when the engine stops due to a little bit of thermal siphoning, and heat soak. This should all make more sense now that I fixed the minutes.

Bob - Similar, I think you're confusing when I shut the engine off as the time it spiked from 190 back up to 208. That's my fault from having the units wrong on the bottom of the chart. As far as oil temp, I am surprised it is so high given the engine load. Though based on the curve, it is likely that it would stabilize around 255-260. I'll have to think on that one. The MCS is rear PTO driven, so definitely a big load on the engine (but not this day). It'd be interesting to see the same ambient day mowing just like this, but with the MCS rolling too. There should be a step function in the temperatures. I have a whole slew of tests in my head I want to test, 3/4 throttle being one of them, though I wish I had a working tach so I could dial it in. Last fall I did a few runs opening and closing the hood, and having the side panels off. These tests clearly reduced air side fan discharge restriction, and increase airflow through the radiator. The RadIn and RadOut temps should separate with an increase in airflow (more efficiency) were I to do this. Need to ponder this and the oil temp more...

Skwirl - That is wild considering that it's been said time and again that the cooling system is borderline undersized. Makes me think there absolutely has to be something going on. As far as oil temp...coolant will follow oil temp a lot closer when there is a liquid-liquid engine oil cooler. Without one, it is normal to have the separation. Oil temp is driven by load and RPM. Since there is no active cooling of the engine oil, it shouldn't vary too much with a change in ambient temperature, as long as it's loaded the same. I feel like it ought to be at least a little lower than it is though.

I could try without the t-stat simply to get some data. Can't hurt. The problem is that It takes about an hour's worth of running full tilt to get the data needed to make assessments. And I don't have that much grass to cut! Will keep pondering on this. Stay tuned.
 

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Aaron, Be careful if you run without t-stat! I'm thinking coolant temp in& out will be lower, but with the same load on the engine, oil temp will be higher. This is based on my assumption that coolant is already passing through the engine too quickly and not absorbing heat.

As far as oil temp stabilizing at 255-260, I'd NEED to see data to verify that! I see a nearly straight line with no curve from just after the 30 minute time. However! If you extend the curve generated from just prior to the 30 minute time, it does look like it will peak out at 250-260! Too confusing to guesstimate! Let's see what future tests/data produce. Bob
 

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I was reading back on this thread. Are you using 50/50 mix for antifreeze? Or your own mix percentage? I may have missed this earlier, but I know water takes heat in and out better than antifreeze. I would try only maybe 30 percent antifreeze to experiment.
Dan
 

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I was reading back on this thread. Are you using 50/50 mix for antifreeze? Or your own mix percentage? I may have missed this earlier, but I know water takes heat in and out better than antifreeze. I would try only maybe 30 percent antifreeze to experiment.
Dan

Or maybe just use a water wetter in the system and no antifreeze...available from racing supply shops. I would only do this as a test however, water wetters don't have rust and corrosion inhibitors (to my knowledge).

The other potential problem I can think of in this situation would be cavitation in the cooling system. Air bubbles don't absorb heat. Diesels use a special antifreeze additive (or at least used to) to reduce cavitation.

I know my Oliver 1775 has a Waukasha engine and it's notorious for metal erosion around the cylinder sleeve bases due to cavitation and time. That won't effect the cooling process but it might be something to consider, as I said air bubbles don't absorb heat very good. Cavitation size air bubbles will not produce excess pressure and may never expose themselves because they are microscopic in size but otherwise they show up as foam. Like an air emulsion.

I'm no expert on cavitation...I just know what the old timer mechanic that rebuilt my tractor engine told me and I had to change coolant canisters with that anti-cav chemical in it on our old Kenworth semi tractors and other diesel engines (not all of them however) at the construction company. Just something to muddy the water I guess.

 
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