June 10, 2019 at 3:00 pm #177063
So after a year or so of messing around with this I have it running on muffs. So far all seems OK except the water circulation, which I don’t seem to be getting.. Has new impeller, opened and checked over thermostat box, etc. The block does not seem to be filling: too hot to hold hand on, only getting some steam from the telltale line I installed using the plug on the starboard bank.
So, have I screwed something up here? Or does this motor not like to run on muffs? Or?
Update: The pump seems to have picked up its prime and the system be working. Some hesitation–maybe I didn’t give it enoiugh volume on the muff. I’m glad I put the telltale on, for peace of mind.
Not sure how much volume I should let come out the telltale without unbalancing the temperatures of the two banks, but I used 1/8″ tube and fittings and the output seems reasonable.
- This topic was modified 10 months ago by amuller.
US Member - 1 Year
Topics: 48June 10, 2019 at 4:14 pm #177071
Not sure where you got your telltale from. Do you mean the hole shown in this picture? If so, that is a relic from the days of water heated automatic chokes. Those were 1/4″ hoses in the choke application, so I doubt your 1/8″ telltale is a problem.
Those motors are as happy as any are when on muffs. I don’t think you were supplying enough water to the muffs.
You must be logged in to access attached files.June 10, 2019 at 4:34 pm #177073
Yes, that’s the opening I used. I used a 1/8″ hose barb and a 1/8″ ID hose to a hole drilled in the pan almost directly below. I used another barb to make sure the hose could not slip out of the hole and spray water all over the power head. Drillng and tapping the very top of the water jacket would be idea but didn’t seem worth the extra effort.
I think you are right about not supplying enough water. I was concerned about over pressurizing the motor–water pressure here is close toi 90 psi–but then I realized that the muffs are spring-loaded onto the leg and would probably relieve excess pressure.June 11, 2019 at 1:52 pm #177146
Your engine has the more complicated water pump that recirculates water back to the pump to help warm it up….The two water tubes are tough to line up unless you use the little plastic sleeves. These sleeves are usually found stuck up on the water tubes… Did you have the thermostat apart? There is a recirculation check valve in there that must be in place and working properly or cooling water will just short circuit back to the pump without circulating through the block…
You shouldn’t be seeing any steam coming from the telltale….June 11, 2019 at 2:19 pm #177147
The first time I assembled it I did not know how to use the plastic sleeves to ensure proper seating of the tubes. So a few days ago I dropped the gearcase down to recheck and use the sleeves as intended. I think it was OK before but I’m confident now.
I think the parts in the plastic box are properly assembled. Water seems to come out of the telltale at a reasonable, regulated temperature. Sometimes it takes a minute for the system to fill and pressurize.
In the water later this week. I intent to keep a close eye on that telltale.
Is there a particular pressure I could look for with a gauge?
Thanks!June 11, 2019 at 6:05 pm #177155
Well, usually the tap for the telltale on these engines is located on the exhaust cover, which is at the beginning of the cooling cycle. But, your exhaust cover does not have a provision for this…Plus, your engine has that return check valve, so not too sure what pressure values you might see. Water pressure gages were introduced for later model engines with the single tube cooling system..
I think you are correct in putting the engine/boat in the water and trying it out, that way you can monitor your telltale. Once the initial air has bled out of the block, you should not see any air or steam spurts….Does your control box have an overheat warning horn? If so, have you checked to see if it is operational? This is another good way of monitoring engine temp. Unfortunately, these things can overheat in an instant, oftentimes you won’t have a chance to see the loss of pressure from the telltale, and the warning horn comes on as the engine is seizing up when overheating occurs at high speeds….
So, I would give it a trial run on the water, have an assistant drive while you monitor the telltale to catch an issue before it overheats badly.June 11, 2019 at 8:02 pm #177158
There is a horn in the box and it works, but I have not checked the heat switch itself. Thinking that the cylinder head cover needs to come off to get it out of the hole, and I haven’t felt like doing that. Is that so? It’s low down, and the manual says it closes at 211 deg F. so I think it might not give very adequate warning anyway.
The service bulletins I’ve seen on adding telltales seem to focus on avoiding airlocks, which makes sense to me: Many modern vehicles have a similar issue: The filler cap is not at the high point of the system, so airlocks can happen.June 12, 2019 at 1:25 pm #177177
I agree, surely would not pull that water cover off the head in order to check the operation of the temp switch. But, I would surely ground the tan harness lead with the key turned “on” to make sure the horn works OK.
And yes, that tap in the block is at the top of the block, but I would think that the telltale hose would clear out any air bubbles fairly quickly. But, again, I have never tried using this port for a telltale tap on one of the older engines….
I think your plan of taking the boat to the water and trying it is the best bet. But, again, bring an assistant to monitor the telltale output just in case there is an actual cooling issue…June 12, 2019 at 11:52 pm #177199
I stuck a pin through the temp switch lead and grounded it and the horn didn’t operate. Am pretty sure I tested the horn when I put the box together. Something else to track down.
Other question: I notice that the two timing “grids” show about a 1-2 degree difference in timing both at 5 deg and 28 deg. I think it is the same point set that breaks, so it would not be due to a difference in the setting of the two sets. Is that right? I’ve checked the idle timing both statically and with a timing light. (The book calls for checking the advanced timing at 4500 rpm and I’m not about to try that on muffs.)June 13, 2019 at 8:54 am #177205
Not sure I understand what you are asking about with the timing grid(s), perhaps if you posted a picture…..Once again, there is no “idle timing” setting for this engine, the 5 degreeBTDC setting is checked when the throttle cam line bisects the throttle roller.
Try sliding the rubber sleeve back on the tan lead, then grounding it with the key on, perhaps you are not making a great ground connection.
And yes, the WOT timing has to be checked with the engine actually running at WOT. Impossible with ear muffs, very dangerous while driving the boat, the best/safest method is backing the boat in the water with a test wheel, which I’m sure you don’t have. You haven’t disturbed the WOT timing screw setting, so I would leave it alone. If anything, I would just turn it inwards a couple of turns to retard WOT timing just slightly.
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