Next hotter plug from QL77JC4?

[CaneCutter79]

Re: Next hotter plug from QL77JC4?

Here are photos of the thermostat assembly after I removed it. This is how it's installed (location of springs, orientation of springs, relief valves, stats, etc.)

These are new spark plugs that have about 2miles of use on them. I decarbed the motor (using the sticky at the top of this forum) and replaced the plugs with brand new fresh out of the package plugs. This is what they look like (probably leading to an entirely different issue but posting pics here just to help with the motor running cooler than recommended issue)

Plugs from cylinders 1 & 2 with cyl. no. 1 being on the right. (as if you're looking at the motor behind the boat)


Plugs from cylinders 3 & 4 with cyl no. 3 being on the right. (as if you're looking at the motor behind the boat)


All spark plugs in order as if you're looking at the motor (cyl. no. 1 in upper right, no. 2 in upper left, no. 3 in lower right, no. 4 in lower left)


Thermostat assembly with housing

 

[clanton]

Re: Next hotter plug from QL77JC4?

Do you have the rubber/plastic seal for the thermostats, can`t tell by photo. Need a photo of the white pressure valve, looks like they are in upside down. What about the rubber grommet inside the block for the pressure valve to seat on. There is one more sparkplug, I think, will have to look for the number. The recircilation hoses, if any can be rerouted for a better idle.

 

[clanton]

Re: Next hotter plug from QL77JC4?

The later engines run about 150 degrees at idle, I would think when every thing is correct you would be close to this number.

 

[clanton]

Re: Next hotter plug from QL77JC4?

Check the temps at the thermostats housing.

 

[clanton]

Re: Next hotter plug from QL77JC4?

I find these plug numbers QL78YC and QL82C. The QL82C for extended idle. I`m NOT saying these plugs work for your engine, you have to look at BRP/Evinrude sparkplug chart.

 

[CaneCutter79]

Re: Next hotter plug from QL77JC4?

Do you have the rubber/plastic seal for the thermostats, can`t tell by photo. Need a photo of the white pressure valve, looks like they are in upside down. What about the rubber grommet inside the block for the pressure valve to seat on. There is one more sparkplug, I think, will have to look for the number. The recircilation hoses, if any can be rerouted for a better idle.

Yes, the seals are new (came with thermostat kit). The white pressure valves are not in backwards. The larger diameter is inside the thermo housing and the smaller diameter portion of the pressure valves are shown in the photo above which is the same diameter of the inside of the coil springs.

What rubber grommet inside the block for the pressure valves? I don't have those and they did not come with the kit. Do you mean the rubber sleeves the valves are seated against inside the thermo housing? If yes, they are new and inside the housing (beneath the valves in the photo above).


This is how the assembly is installed currently - per the manual assembly drawing. I double-checked yesterday to be sure. I may be misunderstanding what you mean by grommet. It's probably the grommet (item #32) in the photo below from the manual.

 

[CaneCutter79]

Re: Next hotter plug from QL77JC4?

After doing a little reading, I think I understand the fear of using a hotter spark plug that everyone has cautioned me against. I DEFINATELY do not want any pre-ignition issues.

So the search for IF or WHY the motor is running cold continues. (I should mention that it has a new stator and the electrical system appears to be running correctly and within spec. I do question the power packs......I need to test those further but if the motor is running correctly, the packs should be good).

Hot Spark Plugs vs. Cold Spark Plugs | E3 Spark Plugs News

 

[CaneCutter79]

Re: Next hotter plug from QL77JC4?

Stupid question but could using the wrong oil mix cause a cold motor? I use a Sea Sense mixing bottle that has all of the fuel to oil ratios listed with the amount of oil per gallon of gas. I couldn't imagine this would be wrong but............one thing I've learned from this motor is to ask questions.

The most recent problem I had resulted from me adding 3-n-1 oil to the timer base and that solved a host of problems. If I had asked a silly question about the throttle lever, it could have fixed my motor problems months ago.

So I'd rather ask than not.

 

[clanton]

Re: Next hotter plug from QL77JC4?

I cannot tell if the valve is right or wrong in the photo. All else looks good in the photo. The thermostat starts to open at 143, will not fully open till a few degrees later. If the pressure valve is working, the only thing left is spring pressure holding the valve in position.

 

[CaneCutter79]

Re: Next hotter plug from QL77JC4?

I cannot tell if the valve is right or wrong in the photo. All else looks good in the photo. The thermostat starts to open at 143, will not fully open till a few degrees later. If the pressure valve is working, the only thing left is spring pressure holding the valve in position.

I thought about spring pressure too. The new springs in the kit are the same as the springs that came out of it.

here's the weird part and why I think the pressure valves are opening before the motor can get hot enough to allow the status open....

Earlier, I said when testing the motor after reassembly, the motor ran with no water coming out of the exhaust ports. After 5 mins, water came out of the left side only with a good flow. Seemed odd and hadn't been that way before. So I reved the motor up just a little (about 1,500rpm) and water immediately sprang from the exhaust port so I had two flowing exhaust ports IMEDIATELY after reving the motor up. That told me for sure that the stats are not opening allowing water out.

Has something to do with exhaust pressure and how the relief valves operate (or not operating correctly). The motor can't get warm enough to open the stats.


Darndest thing is, the motor seems to be running correctly. Unless it's been running incorrectly in the last 4yrs I've had it (which is possible).

 

[Joe Reeves]

Re: Next hotter plug from QL77JC4?

If the thermostats are setting on a cork gasket... cork gasket between the thermostat and thew Bakelite spacer they sit upon, then they and everything else I see in the thermostat graphic is correct.

The thermostats open at some point between 143 to 148 degrees. Why your engine would run cooler than that is a mystery to me... I don't see how that is even possible.

The Champion QL77JC4 spark plug, gaped at either .030 or .040 is the choice plug to use. The gap-less plugs regardless of their heat designation are all cold running plugs and as such are prone to fouling.

Is that engine is running properly, other than running cold? If not, what is the problem?

 

[clanton]

Re: Next hotter plug from QL77JC4?

You could check the springs too see if they match, an auto machine shop can do that. You could shim the springs, just like car valve springs to let the pressure valve open at about 1500 rpms. A lot of work trial and testing to get it right.

 

[CaneCutter79]

Re: Next hotter plug from QL77JC4?

Joe as far as I can tell, the motor is running good.

I am only concerned (paranoid even) that if the motor is cold that it will causethe rings tto stick and carb up the motor thus leading to failure and needing another rebuild. I'll only rebuildit once as that was more than enough for me if iI can do the work myself. And I'm not a technician and don't have the time or money to invest.

So.......I just wanted to see if there was something I could fix it or if there was something that needed to be fixed. If it's good as is, great. I just don't want the rings to stick again and ruin the motor.

I may be way overly paranoid. My mechanic said oil these days (especially synthetic -which I use exclusively) won't gum up rings like they used to with older oils. Provided I run the right fuel mix, clean gas, ethanol treatment, etc. I'm even starting to use Yamaha "Ring Free" additive as precaution.

Like I told clanton earlier, I'm convenced the relief valves are opening up at idle after the motor starts to warm. Not sure why or how that works. The stats should be doing that.

Oh and I've checked the temp of the housing. About 110-115. I can put my hand in the outstream of water from the exhaust without it burning me. It's only about 125ish. So the stats are closed according to the heated water test I did on the stove. They crack around 143-146 and open up above 150.


I even plugged the exhaust holes for 1-2mins to watch the temp rise. No change at all. Nothing....


If it's good and I'm paranoid, just tell me. After investing close to $4k in a motor, you want to be sure it's good. For a LONG time.


As for running correctly, it gets 38-40mph (GPS) at 5,000rpm wot with a 3-blade 17p stainless prop with a lot of cup for bite and bow lift (heavy old boat). Idled smooth around 700rpm under load and occasionally right at 550 and ours with no problem. Hole shot is great with lots of torque.

Just runs cold.

 

[Joe Reeves]

Re: Next hotter plug from QL77JC4?

The "plugged exhaust holes"..... If you're speaking of the two holes at the rear of the engine just below the powerhead, those are exhaust relief holes. Beware of plugging them as you could cause water to back up into the bottom cylinder exhaust ports. See my explanation of the relief holes below.

Paranoid? Probably not.... Overly cautious? Possibly. At any rate, you've done all you can, checked everything properly and as far as I can tell.... you've overlooked nothing. Time to place your faith in your work and go with it.

(Exhaust Relief Ports - Exhaust Housing (Inner/Outer)
(J Reeves)

The long housing between the powerhead and the lower unit is called the exhaust housing. There is a inner housing within it that has a heavy duty seal around the bottom of it, or heavy duty seals around a inner extension between the housing and the lower unit.

The red hot exhaust travels down thru that inner tube and out the propeller with a somewhat supply of water to cool the propeller hub. A good amount of water surrounds and fills the space between the outer and inner tube, otherwise the outer housing would get so hot that the paint would burn off.

Some water pumps, for some reason (differing even when new) exert a great amount of water pressure, and if the exhaust housing seals are in perfect condition, the water fills the tube to a point of overflowing.

This brings into play those two holes or slots, whichever the engine might have, at the top rear portion of the exhaust housing just below the powerhead.

Now, if those two holes/slots weren't there, water would continue to flow up into the cylinders. Water not flowing out of those holes is no concern for alarm UNLESS that outer housing suddenly becomes extremely hot..... the warning horn should sound long before that happens.

The main reason for those holes being there (exhaust relief holes) is that when at an idle, there is an extreme amount of resistance encountered by the exhaust trying to escape due the fact that the outlet via the propeller is now blocked by a wall of water. The escape route in this case is for the exhaust to escape out those two holes, otherwise the engine would slow down quite quickly and die. If exhaust cannot escape, air/fuel cannot gain entrance to the engine.

 

[CaneCutter79]

Re: Next hotter plug from QL77JC4?

Thank you very much for the assistance JB. I don't think I damaged the motor with water as it was less than 2mins plugged. Probably 60 seconds or less because I didn't know what it could hurt and I didn't see any change immediately or after about 30 seconds so I removed them.

I appreciate the breakdown on how the relief valves work. Sounds like I need to leave it alone and enjoy it. I'm going to keep running fuel additives for cleaning to help reduce carbon build up just as a precaution. And using synthetic (Royal Purple) as it is a great product and worth the little extra to me.

Again, thanks to all of you!