Iv got a 93 150 xr6 and had a overheating issue after installing a new water pump kit and man I spent alot of money trying to figure this out and it ended up being a 7 dollar fix go get you a tube of permtex and take the foot back off and put you a bead between the water pump and the exhaust housing on the foot if you look after taking the foot off you'll see there's a small gap an uneven area there allowing exhaust to get in the waterpump chamber hope this fixes it
Hey man great video. And I feel your pain. Did ALL the same crap. 3 rebuilds #3 and #6 cylinder EVERY damn time. I gave up and let someone else look at it and the first thing he did is NDI the carb bowls and surprise!!!! there it was, Carb bowl #3 had a hairline crack in it and causing a lean issue on the bottom 2 cylinders!! I am not sure if you ever got it going, but thats my 2 cents
Check out the buckshotracing77 speed store website. Mike and I collaborated on a new troubleshooting technique for addressing this rare problem. He now offers Flux field viewing film for getting an xray look at the trigger hub magnets. This was how i finally found the culprit. Pretty cool to be able to contribute to the community in this way.
Every cylinder has their own bowl. Carburators have two bowls each! Cylinders 3 and 6 share the same carburator apparently but actually each cylinder has their own carburator. A blocked bowl will affect only one cylinder and only the sparkplug of that cylinder will show a lean condition. The only thing in common for every straboard and port side is the fuel line.
It was actually a faulty coil causing all those gremlins. Went ahead put all new coils on as well as another set of SBs after killing them immediately upon cranking lol and problem solved.
Adam, I am not sure of the previous switch box failure symptoms, but the most common reason I see is loose grounds. If from loose grounds they tend to just pop and are dead and usually both.
Hi Adam, While I did not get a real good look at that piston in the other block, this screams to me that you have a timing issue. A friend lost number 5 cylinder and we found a bad trigger, the piston siezed in the block but the top of the piston was not melted from running lean, it looked alot like yours and the trigger was double firing on number 5 cylinder with number 2. We could see it in the timing light. Since your issue is on cyl 4, I would really watch that timing light expecting a double fire with cyl 1. Good Luck.
Thanks and I've considered that also. I double checked the timing with both 1 and 4 and everything is normal. I didn't see any double fire. I'll definitely take another look though. Thanks!
Im still kicking around your thoughts here....If it was a trigger issue, i should see similar symptoms in both 1 & 4 right? Since the trigger doesnt know which hole its firing, its just sending the low voltage pulse to the SB's that fires both 1 & 4 while the bias carries one or the other to ground right? Seems more like a switchbox bias problem if anything. HMMMM.....I wonder....flywheel hub magnets that charge the trigger, if cracked would the trigger send an extra pulse when the cracked magnet crosses the coil which would double fire that cylinder?
@@SmalltownBassin We pondered those same thoughts with our failure, but the double fire would not happen on #2, only on #5 and it was not every time. I have also had a switch box failure that caused a double fire, this was again found with a timing light and found that #1 would fire with every cylinder on that bank, so a double fire on 3 and 5. Also with the engine at idle you could not hear the double fire, but when you raised it off idle steady some while on the hose you could hear it back firing in the can.
Oh and please dont waste your money on that barfing CDI crap, stick with genuine Quicksilver/Sierra stuff on those electronics and only from know dealers, not ebay. CDI has really gone down hill over the years.
I'm looking into that now. I was thinking electronics in the back of my mind but I keep pushing it further back on the list. Fuel delivery is good, water flow appears good, brand new CDI trigger, stator and reg. Brand new prufex switch boxes. But...I've had a bad sb and stator out of the box before so I'm foolish to rule it out. Thanks man! Fingers crossed you are pointing me in the right direction.
The bad coil was backfeeding and taking out the switchbox immediately. I went through 3 sets of switchboxes before figuring out what was causing it. It killed the same blocking diode everytime, allowing some odd double firing which caused the overheat. Once I put a new set of coils and yet another set of switchboxes on...problem solved.
I guess that the out of time firing caused the gasoline inflammation inside the engine, instead of at the exhaust manifold where actually combustion always happens. Engines don't work as we have been told. The power that moves the piston doesn't come from the expansion of the gases formed after the combustion of the gasoline inside the engine, which actually is burnt at the exhaust manifold which is outside the cylinder. If gasoline is burnt inside the cylinder the amount of heat is huge. That heat will be transferred to the rest of the engine increasing temperature all over the place, showing high temperature at the gauge and triggering temperature alarm. And this cylinder will show terrible consequences while other cylinders will not. If one cylinder runs lean, from a bad seal or a carburator problem, it will show the lean condition with a white color of the sparkplug. But one cylinder might get very hot without a lean condition. The explosion at the right time does move the piston instantly but does not increase the temperature inside the cylinder because gasoline is burnt much later, outside the cylinder once gasoline and oxygen are inside the exhaust manifold. A friend of mine thought me that in any wax candle the light comes from the base of the flame which is not hot at all. We even can touch it! Is the top of the flame what gets very hot afterwards. After the light is made without increasing the temperature. The light is made at the base of the flame and we can touch it because it's at room temperature. An engine works the same way... The ignition at the right time is what builds power with no increase of temperature but the combustion outside the cylinder is what builds a lot of heat outside the engine! Gasoline gets burnt not inside but outside, at the exhaust manifold and even at the exhaust pipe! In racing cars I've seen flames forming outside, at the end of the exhaust pipe.
Hope this helps in some way, carb jetting tables have some different sizes among the 6 cylinders, verify the right jet is in #4 carb. Can send the jetting tables, my manual is 1992-2000 so may cover this engine.
Thanks. Ive got all the jetting charts also. Doesnt do any good for a custom build lol. With .086 mains in all 6 i can assure you it wasnt lean though. Wet as a dog. We will see what the next water test shows then go back into the lower since this issue didnt show up until the cone was installed. Thanks for the help though. Im entertaining everything as the culprit now.
@@SmalltownBassin I tried to link , but the message was block. The link was for high temp thermal decals, as opposed to a heat tab, gave specific temps, poor mans thermal couple on all 6 I thought, but if cylinder is wet, yeesh I don't except maybe use those thermal tapes to assess cooling circulation around the cylinders, to see if the #4 jacket is getting same amount of water within the block as other water jackets. Having a Water press gauge another way to rule out pick up issues at speed and trim. Also a quick thanks, I really enjoyed the engine build video.
Yeah i jetted them myself. All 6 holes have .086 mains. For WH-46's that's a crap ton of fuel. Too much actually. Good idea with the thermal tape too. Thanks!
Does your engine over heats after increasing rpm over 2000 rpm? Mine is a 1998 Mercury 135hp. In my case it looks like a double firing or a clogged poppet valve, because temperature goes up above 1500 rpm growing to 3/4 at gauge and sounding the alarm above 3,000 rpm. But I do suspect about double firing because starting motor stops moving the engine when gasoline reaches the engine. I have to release the key and start again in order to start the dngine at the second or third attempt. Temperature stays perfect at around 1/4 at the gauge after several minutes at 700 rpm. Engine works well until I go into planing speed at 4000 or 5000 rpm when engine gets very hot in less than a minute, anyting above 2500 causes the temperature to start growing and alarm triggers at 3/4 reading of temperature gauge.
@@SmalltownBassinsorry but I don't have facebook and I don't know how to send you a message. Can you tell us here how did you find and fixed your over heating problem, please.
Yep, holes look good. Just the exhaust side of the slug trying to escape the port in liquid form lol. Epoxy plug is up to about a quarter inch below the npt fitting and the top of the npt fitting is about a quarter inch below the pump base. So there's about an inch and a half of head space between the pump base and the epoxy plug. I'll shoot another video of the cone next. Just to go over everything on camera for you guys to help. Thanks again.
Yeah I've considered it but with a 2 piece plate that shouldn't be necessary. This issue didn't show up until I installed the bobs cone but the install is clean.
The oil will begin to emulsify at high temperatures and fill the cross hatching of the cylinder walls with cooked oil glaze. Usually noticeable as a purplish or dark discoloration of the cylinder wall. This adds friction to the rings and accelerates the wear.
Don't let your oil injection fail! Premix is the only way I go. Better to delete the injection and premix before it fails while you still have a usable motor. Just my opinion though.
I'm pretty sure it's switchbox failure. Finishing up the troubleshooting on film this week. Bout to try to witness double fire with a timing light in the dark. Hard to tell in daylight. Bigger question is what's killing my SBs so often? I don't buy cheap knock offs and I've been through 3 sets in less than 2 years. Thinking maybe I have some voltage bleed in the key switch killing them so I'm replacing the switch too.
Thankyou for taking the time to make such an informative video, it was very helpful, keep them coming!
Thank you! Will do!
Iv got a 93 150 xr6 and had a overheating issue after installing a new water pump kit and man I spent alot of money trying to figure this out and it ended up being a 7 dollar fix go get you a tube of permtex and take the foot back off and put you a bead between the water pump and the exhaust housing on the foot if you look after taking the foot off you'll see there's a small gap an uneven area there allowing exhaust to get in the waterpump chamber hope this fixes it
Hey man great video. And I feel your pain. Did ALL the same crap. 3 rebuilds #3 and #6 cylinder EVERY damn time. I gave up and let someone else look at it and the first thing he did is NDI the carb bowls and surprise!!!! there it was, Carb bowl #3 had a hairline crack in it and causing a lean issue on the bottom 2 cylinders!! I am not sure if you ever got it going, but thats my 2 cents
Flywheel hub magnet had a crack causing a false trigger input at the wrong time. Sporadic at low rpm but melts holes at higher speeds.
Check out the buckshotracing77 speed store website. Mike and I collaborated on a new troubleshooting technique for addressing this rare problem. He now offers Flux field viewing film for getting an xray look at the trigger hub magnets. This was how i finally found the culprit. Pretty cool to be able to contribute to the community in this way.
Every cylinder has their own bowl.
Carburators have two bowls each!
Cylinders 3 and 6 share the same carburator apparently but actually each cylinder has their own carburator.
A blocked bowl will affect only one cylinder and only the sparkplug of that cylinder will show a lean condition.
The only thing in common for every straboard and port side is the fuel line.
PULL THE LARGE PLUG AT THE TOP OF THE BLOCK. LOOK FOR DEBRII UNDERNEATH WHICH IS BLOCKING WATER FLOW INTO THE EXHAUST COVER.
I get it dude. It was a bad coil. Thanks for watching!
Replace Diaphragm fuel pump kit. It can leak fuel in to crankcase al righ out or lean out cylinder 3/4
If everything is good over and over you have no problems....
the aftermarket switch boxes have been known to double-fire causing pre-ignition. just something to be wary of OEM only!
It was actually a faulty coil causing all those gremlins. Went ahead put all new coils on as well as another set of SBs after killing them immediately upon cranking lol and problem solved.
Was just your number four cylinder double firing or several other cylinders too?
Where did you get new coils and switch box from?
@@SmalltownBassin
👍👍👍
Adam,
I am not sure of the previous switch box failure symptoms, but the most common reason I see is loose grounds. If from loose grounds they tend to just pop and are dead and usually both.
No loose grounds. I did just witness double fire though. Uploading the new vid tonight. Editing now.
Hi Adam, While I did not get a real good look at that piston in the other block, this screams to me that you have a timing issue. A friend lost number 5 cylinder and we found a bad trigger, the piston siezed in the block but the top of the piston was not melted from running lean, it looked alot like yours and the trigger was double firing on number 5 cylinder with number 2. We could see it in the timing light. Since your issue is on cyl 4, I would really watch that timing light expecting a double fire with cyl 1. Good Luck.
Thanks and I've considered that also. I double checked the timing with both 1 and 4 and everything is normal. I didn't see any double fire. I'll definitely take another look though. Thanks!
Im still kicking around your thoughts here....If it was a trigger issue, i should see similar symptoms in both 1 & 4 right? Since the trigger doesnt know which hole its firing, its just sending the low voltage pulse to the SB's that fires both 1 & 4 while the bias carries one or the other to ground right? Seems more like a switchbox bias problem if anything. HMMMM.....I wonder....flywheel hub magnets that charge the trigger, if cracked would the trigger send an extra pulse when the cracked magnet crosses the coil which would double fire that cylinder?
@@SmalltownBassin We pondered those same thoughts with our failure, but the double fire would not happen on #2, only on #5 and it was not every time. I have also had a switch box failure that caused a double fire, this was again found with a timing light and found that #1 would fire with every cylinder on that bank, so a double fire on 3 and 5. Also with the engine at idle you could not hear the double fire, but when you raised it off idle steady some while on the hose you could hear it back firing in the can.
Oh and please dont waste your money on that barfing CDI crap, stick with genuine Quicksilver/Sierra stuff on those electronics and only from know dealers, not ebay. CDI has really gone down hill over the years.
I'm looking into that now. I was thinking electronics in the back of my mind but I keep pushing it further back on the list. Fuel delivery is good, water flow appears good, brand new CDI trigger, stator and reg. Brand new prufex switch boxes. But...I've had a bad sb and stator out of the box before so I'm foolish to rule it out. Thanks man! Fingers crossed you are pointing me in the right direction.
You are saying it was a bad (ignition?) coil causing the overheating correct? Could you elaborate and explain how this contributes to overheating?
The bad coil was backfeeding and taking out the switchbox immediately. I went through 3 sets of switchboxes before figuring out what was causing it. It killed the same blocking diode everytime, allowing some odd double firing which caused the overheat. Once I put a new set of coils and yet another set of switchboxes on...problem solved.
I am having same problem,is there a bench test for the coils
Is there any way of testing coils?
I'm asking because I see there are 4 contacts on each coil to perform measurements.
I guess that the out of time firing caused the gasoline inflammation inside the engine, instead of at the exhaust manifold where actually combustion always happens.
Engines don't work as we have been told.
The power that moves the piston doesn't come from the expansion of the gases formed after the combustion of the gasoline inside the engine, which actually is burnt at the exhaust manifold which is outside the cylinder.
If gasoline is burnt inside the cylinder the amount of heat is huge.
That heat will be transferred to the rest of the engine increasing temperature all over the place, showing high temperature at the gauge and triggering temperature alarm.
And this cylinder will show terrible consequences while other cylinders will not.
If one cylinder runs lean, from a bad seal or a carburator problem, it will show the lean condition with a white color of the sparkplug. But one cylinder might get very hot without a lean condition.
The explosion at the right time does move the piston instantly but does not increase the temperature inside the cylinder because gasoline is burnt much later, outside the cylinder once gasoline and oxygen are inside the exhaust manifold.
A friend of mine thought me that in any wax candle the light comes from the base of the flame which is not hot at all. We even can touch it!
Is the top of the flame what gets very hot afterwards. After the light is made without increasing the temperature. The light is made at the base of the flame and we can touch it because it's at room temperature.
An engine works the same way... The ignition at the right time is what builds power with no increase of temperature but the combustion outside the cylinder is what builds a lot of heat outside the engine!
Gasoline gets burnt not inside but outside, at the exhaust manifold and even at the exhaust pipe!
In racing cars I've seen flames forming outside, at the end of the exhaust pipe.
Hope this helps in some way, carb jetting tables have some different sizes among the 6 cylinders, verify the right jet is in #4 carb. Can send the jetting tables, my manual is 1992-2000 so may cover this engine.
Thanks. Ive got all the jetting charts also. Doesnt do any good for a custom build lol. With .086 mains in all 6 i can assure you it wasnt lean though. Wet as a dog. We will see what the next water test shows then go back into the lower since this issue didnt show up until the cone was installed. Thanks for the help though. Im entertaining everything as the culprit now.
@@SmalltownBassin I tried to link , but the message was block. The link was for high temp thermal decals, as opposed to a heat tab, gave specific temps, poor mans thermal couple on all 6 I thought, but if cylinder is wet, yeesh I don't except maybe use those thermal tapes to assess cooling circulation around the cylinders, to see if the #4 jacket is getting same amount of water within the block as other water jackets. Having a Water press gauge another way to rule out pick up issues at speed and trim. Also a quick thanks, I really enjoyed the engine build video.
I guess you double checked the jet in #4 was correct size, as high speed jet would show temp issue when testing without a load, blipping the throttle.
Yeah i jetted them myself. All 6 holes have .086 mains. For WH-46's that's a crap ton of fuel. Too much actually. Good idea with the thermal tape too. Thanks!
Possible double spark shown there at 18:20 or so? Could just be my eyes.
Ive played at 0.25x speed and I saw a double spark at the end. Replacing all six coils and both switching boxes was what fix it.
Subbed. Keep’em coming.
Thanks for the sub!
What is you Main jets size number?
Pilot jet size number?
Is it 2.0l
2.4l
2.5l
Does your engine over heats after increasing rpm over 2000 rpm?
Mine is a 1998 Mercury 135hp. In my case it looks like a double firing or a clogged poppet valve, because temperature goes up above 1500 rpm growing to 3/4 at gauge and sounding the alarm above 3,000 rpm.
But I do suspect about double firing because starting motor stops moving the engine when gasoline reaches the engine. I have to release the key and start again in order to start the dngine at the second or third attempt.
Temperature stays perfect at around 1/4 at the gauge after several minutes at 700 rpm. Engine works well until I go into planing speed at 4000 or 5000 rpm when engine gets very hot in less than a minute, anyting above 2500 causes the temperature to start growing and alarm triggers at 3/4 reading of temperature gauge.
Message me on facebook
@@SmalltownBassinsorry but I don't have facebook and I don't know how to send you a message.
Can you tell us here how did you find and fixed your over heating problem, please.
Mercs can be very frustrating at times, and those cylinders look good? No sign of heat? How high up did you fill the water jacket in the gearcase?
Yep, holes look good. Just the exhaust side of the slug trying to escape the port in liquid form lol. Epoxy plug is up to about a quarter inch below the npt fitting and the top of the npt fitting is about a quarter inch below the pump base. So there's about an inch and a half of head space between the pump base and the epoxy plug. I'll shoot another video of the cone next. Just to go over everything on camera for you guys to help. Thanks again.
I will be waiting watching, hope you get it solved.
Have you thought of maybe taking the thermostats out and running fender washers? May be holding water too long building too much heat .
Yeah I've considered it but with a 2 piece plate that shouldn't be necessary. This issue didn't show up until I installed the bobs cone but the install is clean.
@@SmalltownBassin maybe put the old lower unit on and test it that way. Its probably not the issue but never know.
Yeah I'm definitely doing that test. It will at least isolate the problem to the top or bottom end. Thanks!
I changed the water pump bottom plate on my 2.5 after changing the water pump twice.
It stopped overheating.
My issue turned out to be a bad freaking coil. Good input for others though with similar issues. Thanks!
Vacuum leak on #4 causing it to run lean ?
Its a double firing switchbox from either a bad bias, flywheel hub magnet or trigger. Thanks for the input though!
What was that part about purpllish hue from the oil??..
Glazing
@@SmalltownBassin and where or what does that come from?
The oil will begin to emulsify at high temperatures and fill the cross hatching of the cylinder walls with cooked oil glaze. Usually noticeable as a purplish or dark discoloration of the cylinder wall. This adds friction to the rings and accelerates the wear.
@@SmalltownBassin what’s the best way to combat this? To either stop it slow down wear?
Don't let your oil injection fail! Premix is the only way I go. Better to delete the injection and premix before it fails while you still have a usable motor. Just my opinion though.
What size are your carbs wh20?
Poppet valve
Adam,
Did get this figured out?
I'm pretty sure it's switchbox failure. Finishing up the troubleshooting on film this week. Bout to try to witness double fire with a timing light in the dark. Hard to tell in daylight. Bigger question is what's killing my SBs so often? I don't buy cheap knock offs and I've been through 3 sets in less than 2 years. Thinking maybe I have some voltage bleed in the key switch killing them so I'm replacing the switch too.
Check poppet valve
Might be a busted read
Bad coil causing all those gremlins.
You're running lawnmower fuel lines!!
Common! Give me a break. Don't need a PhD to see your problem!