225 efi Sneeze and sludge

**Seanj85** · 10-12-2019, 10:40 AM

1996 merc 225 3.0L efi, motor sneezes on idle and has been spewing out some oily sludge from exhaust. Are these things related? Just took motor apart the other day, reeds are good, cleaned all injectors and fuel system. Has good fuel pressure and used all new gaskets. I'm at a loss here.
Sneeze:
https://youtu.be/I2golQi07T0

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**Motv18** · 10-12-2019, 11:19 AM

Humm is it down on power?

a miss can leave a wet slop add in some head gasket leak and you get bleh. Compression test probably in order. The sounds good on this vid the whiff sounds more like dead exhaust.

The bleed lines can cause the sludge as well normally it will smoke when draining good but occasionally you get sludge as it mixes with reversion water.

If you haven checked stator and could yet I guess dig in testing almost hate saying it.

**Seanj85** · 10-12-2019, 11:23 AM

Originally Posted by Motv18

Humm is it down on power?

a miss can leave a wet slop add in some head gasket leak and you get bleh. Compression test probably in order. The sounds good on this vid the whiff sounds more like dead exhaust.

The bleed lines can cause the sludge as well normally it will smoke when draining good but occasionally you get sludge as it mixes with reversion water.

If you haven checked stator and could yet I guess dig in testing almost hate saying it.

Stator is good, what should I check with bleed lines? Motor is not down on power.

**Seanj85** · 10-12-2019, 01:03 PM

I exploded a lower unit a few weeks back, could something have happened to the lower crank seal when this happened? Could this explain the sludge and the sneeze?

**Merc 2.5** · 10-12-2019, 06:44 PM

That sludge would seem to b powerhead gasket but idk just a guess but really dont explain sneeze. Do all plugs look same after a idle?

**Motv18** · 10-13-2019, 01:12 PM

Possibly the sludge not so much the sneezing or miss.

How did the lower blow up, say bad enough to mess up the drive shaft, or just prop shaft crack and bugger the gear?

if bad enough and all that got twisted up it could have been enough to mess with the crank. Takes quite a blow up to damage much though. More or less second order damage.

**Seanj85** · 10-14-2019, 03:16 PM

Originally Posted by Motv18

Possibly the sludge not so much the sneezing or miss.

How did the lower blow up, say bad enough to mess up the drive shaft, or just prop shaft crack and bugger the gear?

if bad enough and all that got twisted up it could have been enough to mess with the crank. Takes quite a blow up to damage much though. More or less second order damage.

Lower blew up pretty bad was fully loaded with 200 gals of fuel, 3 guys plus bait and gear. it was the counter rotating lower that blew. Originally I thought the carrier just blew out, but when I opened it up there were all sorts of pieces inside it, nothing was salvageable. It was a pretty loud bang when it blew. I am going to pull the boat thursday for the season and pull the powerhead and take a look. Could a shot from the driveshaft really bend the crank?

**Seanj85** · 10-14-2019, 03:22 PM

Originally Posted by Merc 2.5

That sludge would seem to b powerhead gasket but idk just a guess but really dont explain sneeze. Do all plugs look same after a idle?

Bottom plug looks very clean. All other plugs look normal.

**Merc 2.5** · 10-14-2019, 03:40 PM

Sounds like steamed cleaned. Prob powerhead gasket for the sludge , which mite b losing exhaust or sumthin thru it to and causing sneeze. Have u run compression test , maybe head gasket. if so. Comp would show it

**TEXAS20225** · 10-14-2019, 08:17 PM

lower crank shaft seal is leaking!!!! water is mixing with gas and oil making that goop ive seen quite a few 2.5 do it

**Merc 2.5** · 10-14-2019, 08:34 PM

Ya that's what I was trying to say hahaha , guarentee texas is rite , some things dont "register " as easy without eyes on it.

**TEXAS20225** · 10-15-2019, 09:11 AM

thats the most accurate statement ive heard in quite few days

**TEXAS20225** · 10-15-2019, 09:18 AM

the fuel puddles on the inside of the block its about 1/4 recess for the fuel to accumulate on the top of the cap on a 2.5/3.0 and a bleed line carries fuel/oil to top crank bearing via crankcase pressure

**Motv18** · 10-16-2019, 12:58 AM

It could mess up the seal Tex and merc speak of. The shaft is more likely to give out befor the crank. But if one was close to the end the shock could end it. If you were running 5k and locked up and died when it blew all sorts of nasty things could happen.

Doesnt sound that bad though.

**Seanj85** · 10-17-2019, 05:54 PM

Pulled the boat today. Compression tested 90-95 across the board. Let the motor idle and sneeze for a while before dropping lower. attached are a few pics of the plugs. The first 2 pics are port bank (lowest on the right), the next 2 are stbd bank Also noticed some milky sludge inside exhaust cavity in mid.