Merc 135 wont pee - whats this tube do?

[Off-Peak]

Hi gang... Never had any trouble with this motor and today it stopped peeing and got hot with minutes. It sounded as if it was hissing/blowing out air from the pee hole. I blew thru all tubes - no blockage. I pulled the lower end and inspected the pump and blew thru the lower unit tube... No blocks what so ever. The impellar looked fine and the key-way was in place. I could replace the pump, but it seemed fine. Its firm to the touch and has a slight curl in fins and fits tightly in the cover and I can feel the resistence when I turn it in on the shaft. The ONLY blockage i could find was the little tube seperate and found infront the of the water pump. Its a very small tube and I could not pass air through it... what this tube do/what is for as it seems to not connect to anything on the upper unit.

the pic is not my lower unit, but the tube in question is shown in gray - mine is black and only about 5" in lenght.

Your thoughts?

 

[verado7]

Re: Merc 135 wont pee - whats this tube do?

thats where the water tube goes - it might not be sealing properly when the legs in -but- i really suspect your poppets or thermostats are stuck closed -just like a car engine they will overheat the motor ( no circulation) would be nice if they made fail safe t-stats for outboards just like they do now for cars -when they fail they fail open so at least the water circulates but you runs too cold - better than the latter .

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

Thanks...!!

I'm new to poppets and will need to did up my service manual to dig into that... I'm confident the tube is well connected and not failing, yet i still dont know what the little tiny tube does.

I searched for poppets, but didnt find much about a 1990 merc... Any tips on what a FAILED poppet looks like would be helpful as i plan to work on her in the morning. Are poppets common? should my local shop stock these bad boys - I know its an older motor, but I wanna get her back in the water ASAP!!

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

Okay.. i found this....
I plan to set after a new poppet kit and themostat...

should I worry as to "if" my poppet is bad or just replace it?


Any more advice is appreciated... Thank you!!

 

[Chris1956]

Re: Merc 135 wont pee - whats this tube do?

A lot of lower units have a speedo pitot built into them. The small hose in the very front of the LU is for that.

If the impeller is more than two years old, replace it. It is cheap insurance. You can test the thermostats in a pan of water and a candy thermoter. They should open at 140*F

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

A lot of lower units have a speedo pitot built into them. The small hose in the very front of the LU is for that.

If the impeller is more than two years old, replace it. It is cheap insurance. You can test the thermostats in a pan of water and a candy thermoter. They should open at 140*F

thank you - if todays adventures dont fix it, I'll replace the impeller for insurance like you said. Its not that much of a hassle for me, may be 6-8 bolts etc, you know the drill.

This AM I put it back together and we are peeing at 4-5' and its responsive to the RPMs. But, not for some other reason I run hot almost instantly... the buzzer has not come on, (buzzer does work) but its running hot. My brother is coming over to check the timing.

On a side note: 1990 merc 135 - I could not locate the poppet or t-stat on the motor. laugh and call me crazy, but I cant locate them ;-)

 

[Chris1956]

Re: Merc 135 wont pee - whats this tube do?

Thermostats are on cylinder heads, under a two bolt cover, with the telltale hoses exiting from the cover. Poppit is low in the bottom cowl, starboard side. Four bolts I think, with an inner plate as well.

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

Thanks Chris..!! here is the latest.

Played around with the timing and its fine... The motor still runs hot and the heads are much hotter that the block (you may say DUH - I'm just reporting the news). Pulled the water line hoses while running... Water is running thru all channels and appears to be block free... On the way back in the pee stream started to spray in the wind & with about 15 feet to shore the water stopped again.

I'd like to replace t-stats, poppet value, and water pump. I hope to find my CD tonight as i am a rookie to outboards. On a side note, i do have spare head gaskets if you think I would find blockage in the heads themselves...? may be after the t-stats, poppet, and new pump ;-)

please look at this pic - is the location of my poppet? The cover does not look broken however in all the diagrams i see the cover 'covers both holes and has (4) bolts.

Thanks again

 

[Silvertip]

Re: Merc 135 wont pee - whats this tube do?

A thermostat that is stuck shut will cause an overheat at idle. A poppet that is stuck shut will cause an overheat at faster speeds. At idle and slow speeds the engine would never heat up enough to run efficiently so a theremostat is installed to partially block water flow. When engine temp reaches the proper level, the thermostat opens to allow cool water in and the cycle repeats. At speed however, the thermostat would not allow enough cooling water to flow so the spring loaded poppet or bypass valve opens to pass water around the thermostat. If that valve is sticking shut the engine overheats. If the thermostat sticks open, the engine runs too cool at slow speeds and may therefore run poorly. A leaky head gasket can also cause a rapid overheat as comubstion gases enter the cooling system.

 

[Chris1956]

Re: Merc 135 wont pee - whats this tube do?

It appears that 1/2 the cover to the poppit is missing. Snce the mission of the poppit is to pressurize the cooling water, I recommend you investigate. Take the poppit apart, and take all the parts to your locak Merc Dealer and get new ones. Be careful with the remaining poppit bolts. Do not break them. Use some heat and penetrating oil and an impact driver to coax them out.

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

It appears that 1/2 the cover to the poppit is missing. Snce the mission of the poppit is to pressurize the cooling water, I recommend you investigate. Take the poppit apart, and take all the parts to your locak Merc Dealer and get new ones. Be careful with the remaining poppit bolts. Do not break them. Use some heat and penetrating oil and an impact driver to coax them out.

Okay, i will start there and post what I find. Since its Sunday,I called Wastemarine and they have the T-stats for $12 each, but nothing else so I'll either do it all online or go to a local shop. I'm off to open her up...


Thank you!!!

 

[wreckedship]

Re: Merc 135 wont pee - whats this tube do?

Its me... Im at the inlaws a forgot my account password...
So, the Poppet looked great... Came off easy & seemed to have pressure behind it or the sound was water hissing as it hit the bolts I heated to remove them. Not sure. The gaskets were cork and the spring is responsive along with all rubber intact.

I pulled both t-stats and got a shock... I guess the pics speak louder than my words - your thoughts please...???

#1 is the engine w/ poppet removed
#2 is the poppet
#3 is 1 of 2 t-stats... Correct me if I'm wrong, these t-stats are shot???

 

[wreckedship]

Re: Merc 135 wont pee - whats this tube do?

Now Im showing my redneck-side...

I removed what was left of the t-stats and the entire poppet to see what the engine would do... AND...

It ran like a champ!!

Water from the pee tube, water out the exhaust, and waterfrom the hole in the poppet cover. The temp didnt even get to half and I was 90% WOT around the lake... GET_R_DONE!!!! ha!!!

Now I know I am not smarter than the guys at Merc, so please tell me why I need to replace the poppet valve?

I understad the t-stats on the low end, but once the motor hit 140 temp - arnt they just along for the ride?

Give it to me straight - I'm sure there is a good reason and I want to follow whats best for the motor!

Also, the poppet spring appears to be stiff. I read that 8psi is required to move the spring.. hmmm..... not sure what that transfers to, but its VERY firm to squeeze....

Thank again!!!!

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

okay... I'm home... Any feedback is much appreciated. Thank you

 

[Chris1956]

Re: Merc 135 wont pee - whats this tube do?

I did not see a picture of the thermostats, however, the places where they install are pretty corroded. I would replace them for good luck. it alos appeared that 1/2 the poppit cover was gone, is that not so?

It probably makes sense to rebuild the poppit valve as well.

 

[sportsmanphil]

Re: Merc 135 wont pee - whats this tube do?

Why should you put them back? Here is my .02


The engine is designed to run at a temperature range, in which the t-stats keep for you.

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

^ good point.

Thanks guys!!! Here is what I was SOLD, I mean told today at my local merc stealer. The parts guys inspected the poppet and said it was fine the the spring tension was fine. He asked if the impeller had ANY curl in it. I couldnt recall if the curl was only when it ws installed of what, so he SOLD me an impeller.

Next we moved to the t-stats. The current tstats were gone with the exception of the main dome. Not sure why...

So I asked the partss guy why-oh-why do i need these stats etc. He claims that the tstats build up pressure and force clean fuel burning and have to be in there, so he SOLD me a set.

When I told him that it ran at 1/4 of the temp scale with twice the run time and twice the water flow without the poppet & tstats, he offer 'what makes you think your temp gauge works correctly?' - I replied that it seems to work just fine and when it overheated the buzzer sounded and then the engine lost power and failed. He wanted to go down the fatal engine damage route and ask me about wiring on the boat.

Since then I've most of these test and the engine is strong and runs smooth without fail....

On Wednesday, I'll drop the LU - put in new impeller, add the new t-stats and replace the existing poppet valve. Hit the water and record my findings...


Chris, I do see that 'half' the cover is gone, but the other side/port apprear blocked/capped off - I'll look at diagrams closer, but i recall seeing an old style poppet and new poppet on the merc diagrams.

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

the main issue was the waterpump... It was NICE to add the T-Stats and know that the poppet valve is good, but the WP is where it was at. Life is good... I ran it and never even got half-way on the temp gauge.

Now my tach is seeing double ;-) from time to time - come & go.. the tach output would read double. Idle at 1800rpm and gets on plane at 8K.... I know from the sound of the motor that the readout is wrong - off to fix that next.!! Thanks guys!!

 

[Off-Peak]

Re: Merc 135 wont pee - whats this tube do?

UPDATE: Took the boat out in boca grande for 50-60miles and NO PROBLEMS!! It was a great trip and the temp never went past half-way on temp... SWEET!!!