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Old 06 September 2016, 05:26   #1
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Intruder 150hp 1995 Compression Possible Overhaul?

Morning all, hopefully the last hurdle in my rebuild!! Had a few issues with the outboard whilst away last week. I've a horrible feeling it's going to need an overhaul but hoping for any pointers before ripping it apart.

Symptoms are:

-Cutting out on idle intermittently
-Slight miss on idle
-Power through rev range but max revs is 4200rpm
Horrendous noise occasionally in startup which I think is the starter solonoid but would happily be corrected.

Compression results and plugs can be seen in the pics below, compression overall is lower than expects but the bottom 2 cylinders especially is poor.

Plugs had some carbon build up, some wondering if it's worth running a decarb through the engine or if it's just simply past that.

Don't know the history of the engine unfortunately.

Any advice appreciated

Was going to take it up to mj marine before I ran the compression test last night, but don't want to do a massive drive only to be a told it needs overhauling.

Thans in advance

Tom
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Old 06 September 2016, 05:47   #2
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Video

Video of noise
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Old 06 September 2016, 08:34   #3
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looking at your PSI numbers I would say an overhaul is due.Maybe even a rebore if its a merc/mar you can rebore just one cyl,I don't know about other makes.
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Old 06 September 2016, 10:26   #4
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Tom, I compression checked that motor last year all the cylinders were at about 100psi. I would recheck. What tool are you using to run the tests.
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Old 06 September 2016, 10:49   #5
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Hi Chris, just a silverline compression tester, nearly new. Dont have a spare one to hand unfortunately.

Tests done with throttle closed, fuel connected but kill cord off. Didnt take all plugs out to complete though, wondering if it's worth re-running it with all the plugs out and then trying a wet test also.

I've bought some Seafoam as there was some carbon build up on the plugs so i'll run that through also.

Starter issue makes it a pain as it turns over then sounds like it jams, so you have to release and then re-turn. The noise is awful so the neighbors arent favoring me at the moment, need to strip the starter off and have a look whats going on there i think. Video hasnt uploaded for some reason, will try again.

Not sure what else the running issues could be, spark seems good across the HT leads, resistance is good across all the coils and leads (cant test under load), i have read stories of power pack breakdown which caused similar revving issues though.


Prop is 19" need to check what pitch it is though.


Cheers
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Old 06 September 2016, 10:51   #6
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In fact video is showing on my phone but not via laptop :/ is it actually there? lol
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Old 06 September 2016, 11:21   #7
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Did you have the throttle wide open when you ran the compression test ? Also were all the plugs removed ?
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Old 06 September 2016, 11:24   #8
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the noise on the starter is probably the Bendix not disengaging. I would remove and service the starter and lubricate the shaft with some Bendix grease.
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Old 06 September 2016, 11:34   #9
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Quote:
Originally Posted by tom_20000 View Post
Prop is 19" need to check what pitch it is though.


Cheers
19" is the pitch BTW the diameter will be around 14".

19" on a 150 on that hull should be on the money. So it sounds like you have to work through a few issues. Things to check are.

- Fuel flow from the tanks is good, i.e. no restrictions and the tanks are ventilated correctly. Does the primer bulb remain firm after running the engine or does it suck in. This is a sure indication of poor fuel flow.
- Spark Plugs are new and gapped correctly.
- Check the throttle butterfly valves to make sure they are opening fully at WOT.
- Check carbs are clean and no debris, might be worth getting these cleaned by your local mechanic with an ultrasonic cleaner.
- Carbs will need balancing if they are stripped so you need to get this done.
- Finally taking the heads of these engine is not difficult and you can then look at the bores to make sure they are smooth.
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Old 08 September 2016, 14:56   #10
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Quote:
Originally Posted by Chris View Post
19" is the pitch BTW the diameter will be around 14".

19" on a 150 on that hull should be on the money. So it sounds like you have to work through a few issues. Things to check are.

- Fuel flow from the tanks is good, i.e. no restrictions and the tanks are ventilated correctly. Does the primer bulb remain firm after running the engine or does it suck in. This is a sure indication of poor fuel flow.
- Spark Plugs are new and gapped correctly.
- Check the throttle butterfly valves to make sure they are opening fully at WOT.
- Check carbs are clean and no debris, might be worth getting these cleaned by your local mechanic with an ultrasonic cleaner.
- Carbs will need balancing if they are stripped so you need to get this done.
- Finally taking the heads of these engine is not difficult and you can then look at the bores to make sure they are smooth.
Cheers Chris, sorry yes the prop is 14 1/2 inch, 19 pitch.

Ran 2 can of sea foam through the engine, and it's kicked out loads of crap, and incidentally my Compression tester spring a leak mid way through testing!!! Really hoping it's just a dodgey tester, I also checked the motor when I bought it and ideas sure all cylinders were around 100 also, so fingers crossed.

As for the Bendix shaft ive no idea yet how to get at it without removing the flywheel cover which I believe disturbs the timing? Have a seloc manually which im slowly working my way through.

Fuel flow seems good, bulb isn't rock solid, but it's not sucking in in the slightest.

Plugs again are new this week and gapped good.

Got someome with a ultrasonic cleaner so may see him aboit getting the carbs cleaned and find someone to balance them.

If the compression is still low once I've got another gauge I'll whip the head off and see what's going on, got a feeling they've been off before though, in the manual it states they're sealed with an O-ring, yet these I can see gasket sealant squashed out around the sides.

Cheers
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