1988 Evinrude 90 (crossflow v4) - Crank Seals

[JasonAych]

I have a 1988 Evinrude 90 that I can barely get to idle down enough to get to "no wake" without eventually stalling. I am like 90% sure it is a crank seal issue because it runs wonderful otherwise. I've gone through the sync steps and it got a little better as I can carefull bring it down to no wake speeds without stalling it but it doesn't run quite right.


Anyway, I am wondering how to get to the seals? is there an end cap or is the seal simply removed from outside the block? Hoping I do not need to split block.

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Ok. Looking at a diagram, I see it has both an upper and lower bearing cap with the seals. The top seal seems I could just pull from outside of cap. The lower seems I wil need to pull the cap and remove the bearing to get to seal.

My only question is, will the cap pull out without splitting crankcase?

 

[schematic]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Crank seal failure not real common for this engine.
Did you acquire the motor like this or it acted up while you owned it?
Have you:

-compression test
-check for intake leaks
-check idle timing and pointer calibration

The bottom seal can be changed without splitting the block, but the head bearing housing must be removed.

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Crank seal failure not real common for this engine.
Did you acquire the motor like this or it acted up while you owned it?
Have you:

-compression test
-check for intake leaks
-check idle timing and pointer calibration

The bottom seal can be changed without splitting the block, but the head bearing housing must be removed.

Thanks for the thoughts but I have narrowed it down to the seals. One important indicator is the gray foamy sludge coming out the exhaust. Motor is 25 years old, they were not thinking about ethanol back then, good chance the seal is bad. Thanks for confirming about not splitting the block.

 

[daselbee]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Barking up the wrong tree. Look elsewhere. My 2cents. That repair is the most difficult to attempt for a problem such as yours. Why go for the hard fix when so many other possibilities exist? And YES, you do have to split the block for the crank sealing ring replacement. If taking about the oil seals at each end of the crank, then no, you don't have to split the block. Bad seal there will not cause your symptoms.

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

I am talking about seals at each end of the crank.

Motor runs good and will idle all day on muffs. Carbs are clean. 125ish psi on all 4 cylinders. Runs wonderful 1/8th (estimate) throttlle and up. Put boat in water yesterday, started and trolled (no wake, 1/2 mile) out to main lake just fine. Blasted around lake for hours. Tried to troll (no wake 1/2 mile) back to dock. Boat stalled once, started back up, almost stall again a short time later but caught it (neutral then throttled up only). This is a very common theme. Grey foamy sludge out the exhaust. What else do you suggest I look into?

 

[daselbee]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Jason, let me ask you a question for a change....why would bad "end of crank" seals cause the grey sludge you are seeing? Please explain your train of thought.

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Water gets sucked into crankcase through bad seal, mixes with oil/fuel/air mix in crankcase, spits back out through bad seal into hot exhaust . End result is gray sludge.

Bottom line is i mainly work on 50s and 60s Mercs. Most of them, I replaced the seals. The ones I haven't replaced seals on I get the grey sludge. Not the case with others. On top of that the new seals fix idling issues. One motor in particular in recent history was sludging up, I replaced bottom crank seal, and sludge stopped.

 

[schematic]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Thanks for the thoughts but I have narrowed it down to the seals. One important indicator is the gray foamy sludge coming out the exhaust. Motor is 25 years old, they were not thinking about ethanol back then, good chance the seal is bad. Thanks for confirming about not splitting the block.

grey foamy sludge can be caused by incomplete combustion (low compression) or water ingestion. Doesn't mean you have leaky seals...

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

I gave compression readings

 

[schematic]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

is this engine running cold? Are the thermostats removed? If it is running cold it will also sludge and have poor idle as well.

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Normal temps according to gauge.

 

[clanton]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Rerouting the recirculation hoses to the pattern used on the 1990/91 engines will also improve the idle. There was a service letter from OMC covering this.

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

I'd love to see the bulletin

 

[daselbee]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

So you are concentrating on the bottom crank seal....hmmmm....Do you have any water on the plugs? For grey sludge out exhaust, I would think that it would have to be a pretty defective seal. Like torn completely....I kinda see it as picking up water somehow, but only after it warms up, like maybe a cyl crack that expands or something. But truly, the presence of water has to be absolutely verified. It may be just a very rich condition, incomplete combustion, and then mixing with water down in the exhaust chest/prop area. EDIT: if the bottom crank seal was torn so bad as to cause sludgy exhaust drip, #4 plug would be a mess too, or at least show some evidence of water.

 

[schematic]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Normal temps according to gauge.

gauge often measures only one bank. Measure both with a infrared thermometer. What is you max RPM lately? Is it possible you are running with one dead cylinder? These engines run fine on 3 cylinders but of course won't reach max RPM

 

[schematic]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Bottom line is i mainly work on 50s and 60s Mercs. Most of them, I replaced the seals. The ones I haven't replaced seals on I get the grey sludge. Not the case with others. On top of that the new seals fix idling issues. One motor in particular in recent history was sludging up, I replaced bottom crank seal, and sludge stopped.

I've seen these vintage of motors pop out top seals from backfiring when starting. Not common among crossflows. But maybe yours is the first..... LOL

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

Getting max RPMs. 5500. Get there quickly too.

Last time I looked at plugs, a while ago, #4 was cleanest. I will look at them this weekend.

 

[schematic]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

check the temp on both banks.

 

[JasonAych]

Re: 1988 Evinrude 90 (crossflow v4) - Crank Seals

I will be more scientific next time it is running but when running on muffs the past Sunday, both banks felt about the same temp.