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.
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.
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.
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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Chris Stevens
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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Chris Stevens
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.
Re-ran compression, 110-115 on too 4 cylinders, bottom right 70, couldn't get to bottom left (port) due to the gauge fitting g fouling the casing. Gonna strip the head off Tuesday see if there's damage to the cylinder or piston I think. At least too 4 seem good!!
Head removed, found one difference between top cylinders and bottom 2, small lip/ridge on the bottom (6 O'CLock) of the cylinder right at the top (last 5mm). I assume this is the limit of the piston ring.
Some play across the pistons, but it's uniform across them all so i assume this is normal.
Unsure where to go next, thinking of replacing the O-rings and seeing if that makes a difference, failing that i'm guessing rings or cylinder is warped? (will need a bore gauge)
Incidentally most of the small waterways appear to be blocked with salt and calcium build up.
Only other noticeable difference was a large build up of oil in the two bottom cylinders in the ports (exhaust i think, ports closest to centre of engine).
Anyone know much about changing the rings on these, rings appear about £20, but unsure how many more consumables i need to change in the process (bearings/shims etc)?
I would be inclined to get run a few cans of seafoam or similar through the engine to try and de-carbon. It could be you have a ring sticking. Put the heads back on and give then engines a few hours of use before going to the extent of stripping them. The bores look OK to me, as long as they are smooth I would avoid any more cost.
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Chris Stevens
Will do, I've run 2 cans through and it kicked plenty of sludge out, gonna have to wait until i'm on the water to do it again, neighbours weren't happy! Added it direct to the cylinders before will put the last can through with some fuel i guess. Called Mike at southcoast to see if he's got some o-rings. They were pretty stiff. Parts have broken away when i've taken the head off.
Quick update as progress has been made incase anyone else has similar problems, cleaned all the pistons and head up, and replaced the O-rings. Compression was this the same 115 top 4, and 60 - 65 on the bottom right. (still cant get into bottom left until i buy a new gauge). I suspected a fault with the ignition system from what i'd read on other sites, so renewed the HT leads and plugs, and found many sites suggesting power pack issues so installed a new CDi Power Pack unit.
Took the boat out today, consistently hit 5200 - 5400 rpm with a top speeds at WOT of 42 knots which i'm pretty pleased with.
Plugs looks good after the run and the cylinders that are low are still fetching plenty of oil through. Looks like i'll need to look at re boring to resolve the compression issue, but overall the performance of the engine is back on par with no stalling issues and the miss has also disappeared.
Help Please! Can anyone recommend
a) a decent machine shop preferably someone who have experience with outboard engines i guess?
b) where i can go/look to source parts (google only seems to return a sea of US sites)? I know i can get genuine pistons and rings from various suppliers at ridiculous costs but are there any aftermarket parts that are cheaper? Lastly the 3 companies i've spoken to so far didnt know where i'd be able to source a new sleeve or aftermarket pistons.
I'm in Sheffield so the closer the better!
Doing the rebuild myself, so only need someone to measure the damage and carry out the machine work.
Btw, engine is running really well bar the fuel economy, but the low compression on two cylinders isnt giving me the confidence I want on longer trips.
