45hp chrysler blowing bubbles after impeller change

[Jan Svade]

Finally, got everything in the powerhead running ok and on the last test before taking it out found that the impeller was ripped up. Changed the impeller over and got a stream of water out, although weaker than the previous setup. I took it on the water and it pumped water ok but was blowing bubbles out the exhaust at idle. It never used to blow bubbles like this, and the only time I saw it do this was when I put my finger over the pee hole during testing a while ago.

It would seem that there is a blockage somewhere that is restricting the air (and water) out of the pee hole. Does anybody have any pointers on where to start looking?

 

[fucawi]

Re: 45hp chrysler blowing bubbles after impeller change

Impeller ripped up ....where did the bits go ???..Exhaust side plate off .....thermostat out ....compressed air up the pump outlet pipe...etc

 

[wickware]

Re: 45hp chrysler blowing bubbles after impeller change

1. Would it be normal to get exhaust bubbles out the exhaust?
2. I also understand your point if this is excessive over your past observations. Could the new impeller cause this?
3. Is your overheating alarm system working? Have you noticed any signs of abnormal heat feeling the engine?
4. Please describe the old impeller?s damage, " ripped up", in more details or post a pic. Were parts of the impeller
missing or just worn bad??

Good Luck! jow

 

[Jan Svade]

Re: 45hp chrysler blowing bubbles after impeller change

Impeller ripped up ....where did the bits go ???..Exhaust side plate off .....thermostat out ....compressed air up the pump outlet pipe...etc

The pin spun inside the impeller and created a groove. Top sections of the impeller also fused to the inside of the housing. It seemed to be all accounted for except maybe for some small crumbs. I will dismantle and look for a blockage, although the hose up the powerhead inlet seemed to flow through freely.

 

[Jan Svade]

Re: 45hp chrysler blowing bubbles after impeller change

1. Would it be normal to get exhaust bubbles out the exhaust?
2. I also understand your point if this is excessive over your past observations. Could the new impeller cause this?
3. Is your overheating alarm system working? Have you noticed any signs of abnormal heat feeling the engine?
4. Please describe the old impeller’s damage, " ripped up", in more details or post a pic. Were parts of the impeller
missing or just worn bad??

Good Luck! jow

1. Not the big bubbles that I am seeing.
2. I don't think so. The replacement is from another outboard I have seen pump water ok.
3. I don't have an alarm, and the engine is not excessively hot, although I only took it 500m out and in from the boat ramp.
4. See above. No large parts of the impeller were missing.

Thank you

 

[fucawi]

Re: 45hp chrysler blowing bubbles after impeller change

bubbles in my book implies detergent ....did you lube the rotor with washing up liquid etc ?

 

[Jan Svade]

Re: 45hp chrysler blowing bubbles after impeller change

bubbles in my book implies detergent ....did you lube the rotor with washing up liquid etc ?

They are definitely air bubbles. Like a large air hose is under the water. I used grease on the impeller before putting it in, no detergent. I will not be able to dismantle until next weekend and let you know if I find anything.

BTW how does the exhaust route through both the bottom exhaust and the pee hole chamber?? Does it go through one then the other or equally through both?

 

[Frank Acampora]

Re: 45hp chrysler blowing bubbles after impeller change



If what you are calling the "pee hole" is the round vent at the back of the engine, this is the idle relief vent. When the engine is sitting low in the water--like at idle-- backpressure builds and exhaust would normally be refluxed into the ports and cylinders. The idle relief vent reduces this backpressure by venting exhaust out the hole. The engine will be less likely to stall and will idle better.

TYPICALLY when running, water is passed through the block and head then exits into the leg along with the exhaust. On muffs or during idle, water and exhaust will spit out the idle relief vent. At higher speeds, the leg fills with water and a steady stream will or should exit the hole along with some exiting the exhaust snout. Exhaust will preferentially exit the snout which is now much higher in the water. The water pump itself should not cause any bubbling. However, you should recheck to be certain the water pump is not ingesting air.

Look closely at the attached photo and you will see the stream of water exiting at speed.
Depending upon the engine and idle speed, at idle, there may always be exhaust venting through the snout, bubbling under water.

If you are absolutely sure this is a new occurrence, remove the six screws holding the two halves of the shroud and remove the shroud. The idle relief vent cover is held to the leg with two screws--do not destroy the cork gasket under it. In the leg behind the vent cover held with the two screws you will find two holes. Probe the holes to see if they are clogged.

BTW: If you ever need to remove the powerhead, there is a bolt hidden under the idle relief vent cover.

 

[wickware]

Re: 45hp chrysler blowing bubbles after impeller change

Frank, Good Info! Was I two screws away when I tried to see and understand the pressure relief and coolant water connections exiting these ports attached? At this point I felt my exploratory work vs a problem should end after I felt I saw a dead-end.

BTW: I changed the impeller and cleaned the 1970 35 HP Chrysler in 2010 since the embarrassing Pics attached. I have avg about 10 short fishing trips per summer since 1985 (6-12 gallons) in North, Tx depending on the fishing conditions. jow

 

[Jan Svade]

Re: 45hp chrysler blowing bubbles after impeller change

View attachment 129850

If what you are calling the "pee hole" is the round vent at the back of the engine, this is the idle relief vent. When the engine is sitting low in the water--like at idle-- backpressure builds and exhaust would normally be refluxed into the ports and cylinders. The idle relief vent reduces this backpressure by venting exhaust out the hole. The engine will be less likely to stall and will idle better.

TYPICALLY when running, water is passed through the block and head then exits into the leg along with the exhaust. On muffs or during idle, water and exhaust will spit out the idle relief vent. At higher speeds, the leg fills with water and a steady stream will or should exit the hole along with some exiting the exhaust snout. Exhaust will preferentially exit the snout which is now much higher in the water. The water pump itself should not cause any bubbling. However, you should recheck to be certain the water pump is not ingesting air.

Look closely at the attached photo and you will see the stream of water exiting at speed.
Depending upon the engine and idle speed, at idle, there may always be exhaust venting through the snout, bubbling under water.

If you are absolutely sure this is a new occurrence, remove the six screws holding the two halves of the shroud and remove the shroud. The idle relief vent cover is held to the leg with two screws--do not destroy the cork gasket under it. In the leg behind the vent cover held with the two screws you will find two holes. Probe the holes to see if they are clogged.

BTW: If you ever need to remove the powerhead, there is a bolt hidden under the idle relief vent cover.

I checked under the cover and both holes are clear.

I had a thought. I have previously been running on one cylinder only (no bubbling) but have now got both cylinders firing (bubbling) Could this be the exhaust venting though the snout due to the high idle? It is currently idling at 1500rpm. I will adjust the idle down and check.

BTW there were 3 other chryslers at the boat ramp today and all running (although one took a while to start )