1988 XR4 150 black max starting issue

[mga]

i'm at my wits end with this. I just replaced the head gaskets, fresh fuel, checked everything I could think of, charged battery to full. (non-ethanol gas only!)

when I try to start this motor, the starter will engage and turn the fly wheel. the motor fires for a second and the starter then disengages immediately. This keeps happening no matter what I try. Once in a blue moon I might get it to keep turning over for a few seconds and it wants to fire up, but won't.

Last year we put it in the water and had a hard time keeping it running, but once we got into open water, the damn thing flies! That was last year, now it just won't keep turning over. Hit the starter...turns the flywheel and as soon as it fire up it stops and the starter disengages.

If I don't get this thing running wife wants me to get rid of it :(

I might be able to post a video of what it's doing....argh...no can do

[Merc 2.5]

Is starter kicking out rite b4 it tries to start?

[mga]

yes.

I finally got a video of it up on youtube:

https://youtu.be/XemXvHrZNMQ

[Merc 2.5]

Your battery sounds weak to start with? I've had couple do that also but never had a prob starting, I would start by charging, checking,swapping batt.

[Merc 2.5]

After u get a batt with good charge on it, mite try pulling the plugs and see if it does it then if batt doesn't help
With no plugs should wheel ritenover

[FORBESAUTO]

Sounded like when spinning over at around the 14 second mark, you may have had cylinder with low compression as you can hear the rpm speed up as it went by the weaker cylinder. Pull the plugs and do a compression check. The change in cranking speed may be causing the bendix on starter to disengage

[Merc 2.5]

Forbes has a good point there. Then again my cousins motor I was working on (ignition ) did same thing with 130 on all 6, but it would crank little longer b4 kicking out? I've always been curious to this fix?

[mga]

ok, i'll pull the plugs.....done! IT SPUN LIKE A CHAMP....didn't disengage at all.

I just put all new head gaskets in it, I hope it's not a compression issue.

[Merc 2.5]

U have compression gauge? Its worth checking, forbes Is very knowledgeable bout these things

[Merc 2.5]

A very good mechanic can hear a low compression cyl by cranking it over, just sayin but may not b ur case. I think I would still at least try a battery just see what happens , yours sounded like it was struggling little

[mga]

I have a gage, i'll check first thing in the morning. I appreciate you guys brainstorming this with me...it's been driving me nuts for a long time. the forum is almost therapy...lol

i'll post what the gage reads tomorrow.

[FORBESAUTO]

Basically any time the flywheel spins faster than the starter, the bendix with disengage. Often caused by hitting on just one or two cylinders, enough to speed up flywheel to kick out starter but not enough to keep it running. Didn’t sound like I ever heard it actually hit. Sounded more like a combination of starter dragging (probably not enough amps from battery) then a brief speed up of rpm from a weak cylinder causing lazy ole starter to loose contact with flywheel and disengage. If at all possible I think a compression test would be next thing I would check. Not only look for a low cylinder, but an abnormally high one as well indicating maybe water or excessive fuel in cylinder

[Merc 2.5]

Basically any time the flywheel spins faster than the starter, the bendix with disengage. Often caused by hitting on just one or two cylinders, enough to speed up flywheel to kick out starter but not enough to keep it running. Didn’t sound like I ever heard it actually hit. Sounded more like a combination of starter dragging (probably not enough amps from battery) then a brief speed up of rpm from a weak cylinder causing lazy ole starter to loose contact with flywheel and disengage. If at all possible I think a compression test would be next thing I would check. Not only look for a low cylinder, but an abnormally high one as well indicating maybe water or excessive fuel in cylinder

And when I was working on cousins (ignition ) prob, wasnt firing a couple, it was doin it to , when I got ignition straightened out ,all was good. Ok so forbes is defianltly on sumthin here. , check compression and check your spark

[mga]

Basically any time the flywheel spins faster than the starter, the bendix with disengage. Often caused by hitting on just one or two cylinders, enough to speed up flywheel to kick out starter but not enough to keep it running. Didn’t sound like I ever heard it actually hit. Sounded more like a combination of starter dragging (probably not enough amps from battery) then a brief speed up of rpm from a weak cylinder causing lazy ole starter to loose contact with flywheel and disengage. If at all possible I think a compression test would be next thing I would check. Not only look for a low cylinder, but an abnormally high one as well indicating maybe water or excessive fuel in cylinder

last week, some guy said he did a compression test...they all read from 110 to 125. we thought it was most likely bad head gaskets, which is why I bought new ones and installed them. if I still have low readings, does that mean the rings could be shot?

[FORBESAUTO]

120 ish is about normal. Having someone do a leak down test is ya best bet to tell condition of cylinders/rings. The issue you got going on will only be caused by one being way out in left field or something causing erratic speed changes in flywheel or starter.

[Merc 2.5]

I haven't ever seen a blowed or bad head gasket unless something caused it like a over heat or something. I believe u do need check compression, the may be something else goin on ? If those compression #s are correct then u are at the max allowance for compression differences cyl to cyl,

[KIRCHNER]

Try at idle setting, choke on. no throttle. shoot a little gas'oil mix in air box.

[mga]

I haven't ever seen a blowed or bad head gasket unless something caused it like a over heat or something. I believe u do need check compression, the may be something else goin on ? If those compression #s are correct then u are at the max allowance for compression differences cyl to cyl,

the head gaskets were definitely shot. the person I bought the boat from wasn't too honest about it's history and later told me it over heated a few times. when I removed the old ones you could see where water was leaking into a couple cylinders because the gasket was deteriorated.

maybe I can post a pic of them today. you can see the top one even has a hole in it. both show carbon leaking from the cylinders into water ports ( I believe )

[FORBESAUTO]

Yep, them is cooked. Possible it could have warped a head, or worse the sleeve register shifted or sunk. Do your compression check, if ya find one out in left field, you’ll need to pull that head and check both the head and block for straightness and low spots with a straight edge.

[mga]

Yep, them is cooked. Possible it could have warped a head, or worse the sleeve register shifted or sunk. Do your compression check, if ya find one out in left field, you’ll need to pull that head and check both the head and block for straightness and low spots with a straight edge.

apparently my compression tester must have walked away, so I had to order a new one...it'll be here Saturday, so, i'll post the results then.

thanks!!!

[mga]

ok...finally arrived.

starboard side from the top cylinder: 105 105 110
port side from top cylinder: 105 115 120

am I in trouble?

[nitro_rat]

ok...finally arrived.

starboard side from the top cylinder: 105 105 110
port side from top cylinder: 105 115 120

am I in trouble?

Those numbers don't look good, see above (or below):

Yep, them is cooked. Possible it could have warped a head, or worse the sleeve register shifted or sunk. Do your compression check, if ya find one out in left field, you’ll need to pull that head and check both the head and block for straightness and low spots with a straight edge.

[mga]

ok, thanks. i'll pull the heads tomorrow. what bothers me is I did put new head gaskets in and the readings didn't change much from when we checked them with the bad head gaskets.

if I have a serious problem with this motor I might just call it quits. I don't have the money to invest in heads or block work. this is disappointing, so say the least.

but, let me ask this: IF I find that the heads are warped slightly, would it be possible to have them machined flat and still use them? I have a friend who owns a machine shop who can do them.

[mga]

ok, so I pulled the heads and checked for flatness. they both appear to be OK.

on to checking the sleeves?

coils on #1 and #3 are not firing...ARGH!

[Merc 2.5]

Post pic of your bores if you can. Any scaring/scuffing?

[mga]

Post pic of your bores if you can. Any scaring/scuffing?

actually, no, I wiped them and they are quite clean and no visible scores. they had carbon in them..... (?)

[Merc 2.5]

Well no scuffs a good thing , carbon build up would stick a ring maybe, but prob not 4 out of 6 tho . if it had got hot ,and access to bore gauge, I'd check for roundness , could had got hot enough to distort cyl sleeve possibly.

[FORBESAUTO]

ok, so I pulled the heads and checked for flatness. they both appear to be OK.

on to checking the sleeves?

coils on #1 and #3 are not firing...ARGH!

To check for shifted or sunken cylinders, lay straight edge long ways on deck so that it’s touching on both ends of deck, check for any low spots at each cylinder where seals against gasket from side to side of cylinder. Straight edge should touch consistently across each cylinder and deck surfaces. I was actually expecting to see even more of a difference in compression from what I thought I heard in video, sounded like one had about nothing, guess my ears need to be recalibrated lol

[nitro_rat]

I was actually expecting to see even more of a difference in compression from what I thought I heard in video, sounded like one had about nothing, guess my ears need to be recalibrated lol

I would test the ears on something "live." Never recalibrate your ears based on something you heard in a video.

:D

[mga]

I would test the ears on something "live." Never recalibrate your ears based on something you heard in a video.

:D

first things first, I guess. i'm going to order two new coils. the manual said they should be .05 ohm to .06 ohms, when I checked the two bad ones, they read 6.0ohms.

also, which I thought might be an indicator, was raw oil in the exhaust. to my inexperienced eyes, that told me at least one plug was not firing. am I correct?

i'll check the flatness of the sleeves and once I get the coils back in, i'll find some one to do a leak down test...or, can I do that myself?

[nitro_rat]

Our very own "balzy" can hook you up with a nice leakdown tester of his own manufacture.

[mga]

not much more i can do until i get my two coils....ordered them.