Signs of a bad head gasket - '89 Mariner 200

[tristanlee85]

Originally I was trying to troubleshoot a terrible hole shot after a new jack plate (see https://www.screamandfly.com/showthread.php?344021), but now I have a feeling there is more to not able to get up on plane than just my set back.

Last weekend, while trying to get up on plane with a steady 4k rpms, the motor completely shut down and would not crank over. I thought a ground connection was crap because I replaced the starter over the winter and figured I didn't get the main power cables tights. After messing around with that and knowing the connection was good, I tried again and it cranked over. Thought it was simply electrical.

Later that day, same thing happened while up on plane. After taking the hood off, there was a good bit of water in the cowling. I had a leak on one of the lower water lines and the seal around the regulator/rectifier was leaking. Fixed those and tried again.

Today, just as soon as I got out of the idle zone to take off, it struggled to get the rpms up and then just immediately died. No stuttering. Just completely shut down and wouldn't crank. I trimmed all the way up thinking it had to have been getting water in the cylinders and trimming would possibly help pour it back out through the intake. Well, something poured out anyway. I could see a mix of oil and some fluid (water or gas, assuming water) dripping from the intake. So I am thinking head gasket at this point. I had to bump the starter a number of times to finally get (what I assume) the flooded cylinder to finally clear and crank over.

It idles fine and has no problem revving up, but as soon as it gets under heady load it is done.

I checked compression (cold) after I brought it back and all cylinders were reading 120 - 125psi. Looking through the plug hole, all pistons look to be the same - oil on the plugs and on the top of the piston. None of the piston tops look washed out.

I was hoping to have crap compression in a cylinder to lead me toward an obvious bad head gasket, but I suppose there are other ways to have a blown gasket with compression.

I also feel like it runs hotter than it should. I don't trust my AutoMeter gauge to be terribly accurate, but the temperature will climb to 210 - 225* if I am cruising. The temp alarm has went off in the past and I babied it back (when the water pump was bad). The excessive heat also leads me to a head gasket that only may be leaking under heavy load.

All temp sensors and water pump are new (OEM), lines and cavities for the cooling system were flushed over the winter with no blockages at all.

Any reason why I shouldn't start replacing the head gaskets? I am not sure what else could be causing this.

[Merc 2.5]

Usually a comp guage will point u at a gasket but sounds like it's ok, 210 225 is way way to hot I thought the alarm was supposed go off round 180 190ish. What bout ur poppet ??

[flabum1017]

it's possible it's seizing from overheating. My 140 Johnson did the same thing a few times til I found the cause of the overheating. Take a good look at your cylinder wall for scuffing/aluminum transfer. Other possibility is something in the ignition system is getting too hot and shutting down. Need to address the overheating mainly, but also look for secondary damage due to the overheating.

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[tristanlee85]

Usually a comp guage will point u at a gasket but sounds like it's ok, 210 225 is way way to hot I thought the alarm was supposed go off round 180 190ish. What bout ur poppet ??

That is why I don't trust the gauge reading. It may not be properly calibrated to work with the resistance range of the OEM temp sensor.

Here is the reading at idle with constant cold water from the hose using my nose cone adapter:

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After I removed both the gauge and alarm temp sensor, using a Harbor Freight special infarad thermometer, I measured the 2 heads at the same spot:

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Starboard is a bit higher than port side.

Here is a video of readings above each cylinder:
https://youtu.be/mzYcZwwfAug

And lastly, which is very surprising to me, is the result of unplugging each plug wire one at a time and listening to the difference. Notice the top 2 cylinders on both heads have very little change when the plugs are removed. Only the bottom 2 have significant idle change when unplugged. Maybe that is how the ignition system works... I don't know. I know on a typical 4-stroke engine in your car, idle will change immediately if any 1 of the plugs are disconnected. 2-strokes may be different. This is all new to me. Could be the other 4 kick in at above idle. I'm just spit-balling ideas at this point.
https://youtu.be/NZdZflgVJTM

[rock]

If it were mine at this point I would dial indicate and mark each cylinder on the flywheel. Then check each cylinder with a timing light. This will tell you if there is a spark or not and if it's occurring at the proper time. This will also expose possible cross firing issues.
You did amaze me by not getting knocked on your ass pulling those plug wires. I even look at them too close and I get nailed.

Rock

[Merc 2.5]

I'm with rock. Noway I'd grab those by hand and prob standing n water , u prob got sum switch box issues. sounds ok on hose but then again 2 or 3 of the plug wires didnt make any difference to the idle, grab a timin lite and see if it will lite up on all the wires. Pull plugs and see if u got sum really black ones

[tristanlee85]

I pulled all the coils and tested the primary and secondary resistance and they were all the same - not identical values but consistent. I swapped the plugs around and still the same with the bottom 2 making the most impact at idle. In fact, I pulled the wires from the top 4 plugs so it was only idling on the bottom 2 and while I could tell a difference in sound, it was still idling better on the bottom 2 cylinders than all cylinders minus one of the bottoms.

I used a timing light and it was flashing for all wires.

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At idle, the starboard wires were all timing at 4* to the right of the 0. On the port side, I was only able to pick up the .462 all the way to the left of the 0. All wires on each head were consistent with each other.

I did notice this crack, which looks like it leads to one of the boxes on the starboard side. I couldn't find a diagram online as to what they 2 solenoids (?) do. Edit: these are for the trim
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The other solenoid below what is pictured here isn't cracked. Not sure what this could indicate.

This is difficult to diagnose because none of this testing is happening under load where the problem occurs.

[tristanlee85]

Could this be a stator issue causing weak spark/no spark under load? I had replaced the voltage regulator/rectifier either last year or the year before using a new CDI unit.

[flabum1017]

That solenoid is for the trim/tilt..... blue wires are up, green are down.... the starter solenoid will have yellow/red wires. The cracked one may have gotten hit by the cover while being put on.

You will need either a spark gap tool or a KV meter to check for how strong the spark is

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I like using the KV Meter because you can check the spark with it running.

[flabum1017]

As for the four being weak on power, I'd be doing a sync and link on the carbs..... the bottom carb might be cracked a little at idle making the other 4 cylinders seem like they are not firing as well.

[Motv18]

When you swapped the plugs did you see a different look on them after swaping.

I would start honestly whit number 1 and 2 pulling the wire and idle not changing means it wasn’t working.

[Motv18]

When you swapped the plugs did you see a different look on them after swaping.

I would start honestly whit number 1 and 2 pulling the wire and idle not changing means it wasn’t working.

[FMP]

How much are head gaskets , how many places could it be sucking or seeping water? Process of elimination.

[flabum1017]

How much are head gaskets , how many places could it be sucking or seeping water? Process of elimination.

I would think he would have clean plugs if he were pulling in water

[89Talon18]

7 pounds of water pressure at idle on the hose? Whats your water pressure when your running wide open

[FMP]

Where's the eggnog coming from drooling out the carb?

[Motv18]

Mist from the water leak getting sucked in.

Try fogging it through the carbs with sea foam.

Ive seen something similar on a submerged. With the eggnog. Left his plug out and barely got it out in time flooded the cowlings and died halfway up the trailer.

[tristanlee85]

When you swapped the plugs did you see a different look on them after swaping.

I would start honestly whit number 1 and 2 pulling the wire and idle not changing means it wasn’t working.
I pulled the plugs, cleaned the oil from them using brake cleaner and put them back in. Let it idle for 5 mins on the hose and checked them, both were wet and looked very similar. Also, when I remove the plug wire and put it back on, you can hear it arcing to the plug right before I reconnect it. It is getting spark. Just a matter of is the spark strong or is it not getting enough fuel.


How much are head gaskets , how many places could it be sucking or seeping water? Process of elimination.


I would think he would have clean plugs if he were pulling in water
Right, my initial thought was head gasket, but all plugs are pretty consistent with oil residue. I would expect a clean plug and/or piston if I was pulling in water. After the good compression, I am ruling that out.


7 pounds of water pressure at idle on the hose? Whats your water pressure when your running wide open
Usually between 15 - 20psi. If I am idling in the open water, then it is down around 3psi or so. Enough to have a consistent flow through the telltale.

[tristanlee85]

Where's the eggnog coming from drooling out the carb?


Mist from the water leak getting sucked in.

Try fogging it through the carbs with sea foam.

Ive seen something similar on a submerged. With the eggnog. Left his plug out and barely got it out in time flooded the cowlings and died halfway up the trailer.
What dripped out from the intake was not an eggnog mix like you would normally get mixing oil and water. It looked more like an oil and gas mix with how fluid it was. There was not a lot, but enough to make me notice it and [i]think[i] that I might have been sucking in water.

[tristanlee85]

I did a good bit of testing today on the ignition components. Using the table here (https://www.outboardignition.com/page39.asp, very last row on that page is my engine), I verified the correct OHM reading across the stator, trigger, and ignition coils. The only thing I couldn't test was the DVA because I didn't have the proper tool, but I have an adapter coming tomorrow that will help me read that voltage.

If the voltage checks out, I am going to assume carbs is the next thing. I can grab a bottle of Sea Foam and put it through the carbs with the cover off. I tried that tonight with starter fluid to see if that would make a difference. My expectation was that if it wasn't getting enough fuel, the starter fluid should give me an increase in noise. I felt like it actually bogged the engine though, meaning it had enough fuel and I was starting to flood it.

[FMP]

So it's running hot 225° , maybe spraying enough to stall and hydrolock it so it won't turn the crank.

[tristanlee85]

So it's running hot 225° , maybe spraying enough to stall and hydrolock it so it won't turn the crank.
I suppose it is possible... but I don't trust the gauge reading. The buzzer from the control box would be going off well before then if it really were 225*. And my infarad reader shows the cylinder head temp is significantly lower than the gauge reading.

It's 65* here right now and I just walked out and turned the key forward and the needle is reading 125*.

[FMP]

But the lock up happened, so where's the entry. Adapter, cracked jacket, head, spray from leg?

[tristanlee85]

When I get my DVA meter for checking the stator, I'll be doing the tests on the water. Assuming that it immediately cuts out and shuts down during the hole shot, I'll pull the plugs and see if any fluid runs out. I didn't have the tools on me last time on the lake to verify this.

[FMP]

Nothing ign will stop it from rotating. While your at it cut the heads a bit. A complete disassembling might be the way to correct any hidden issues.

[Dave S]

Could be lower crank seal pulling water......pull off the small hose that runs to the top bearing and see whats in it. cracked exhaust plate?........1/2 9/16 7/16 inch wrench and ya got a pile of parts to inspect......

[tristanlee85]

Well, "good" news. It is not the engine. The water that I said was coming into the cowling was the poppet valve and foam seal that came with my new CDI rectifier. It had deteriorated within a year and was letting water out under pressure. Fixed both of those with some clear silicon RTV.

The spark/ignition issue was a minor problem. I didn't seem to be getting strong spark on cylinders 1 and 2. Understanding how the trigger works, it lead me to believe that was faulty. Because I already had a new rectifier on there from CDI, I decided to go all out and get a new stator, trigger, and 2 new switch boxes. Didn't want to leave anything to chance that could fry existing components. After removing the trigger, I can see cracks all through it. If it actually wasn't faulty, I believe it was coming up on the end of its life.

The bad news is that the lower unit is what was locking up. This explain why it felt like under load it just wasn't getting enough fuel and would slowly seize up. If it were water in the cylinders, that would lock up immediately, or at least bend a rod in the process. It also explains why after waiting a bit, I was able to start to turn it over again. The load at full throttle was enough heat the bearing up to seize it and as it cooled and contracted, allowed me to turn it over again.

Sadly, I spent too much time and money focusing in the wrong area. And I did not check my oil like I should have so shame on me. Luckily, I called a mechanic today to explain the situation and brainstorming he was telling me about a customer of his that had a similar issue - everything ran fine and idle and low throttle, but once opened up things seized. Sit in the water for a bit to cool down and it freed up. Glad he shared that experience or I never would have found this.

Now to fix the lower unit...

[tristanlee85]

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What used to be gear oil is water with a little bit of metal.

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Hard to see zoomed in but those bearings are all chewed up.

[tristanlee85]

According to this diagram, I don't see anything retaining the pinion gear down inside the gear box. I have the retaining ring (#17) removed and see that the bearing (#16) is destroyed. I assume it is a press fit down in there and I should be able to now pull the shaft out. I don't need to remove the carrier bearing assembly first do I? I seems like the drive shaft would prevent that from being pulled since it would be caught on the pinion gear.

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[rock]

You must remove carrier so you can get to the nut holding the pinion in place.

Rock

[Dave S]

ya.... why b/ other.... just get a nudda case.......ckh the areas scrap yard.... or yammi dealer for goodies.....JMO......$500 just a gear set....just find used....

[tristanlee85]

I pulled the carrier bearing and everything is good on the inside, just the bearing around the shaft is shot. I don't want another case (unless I get another as a backup) because anything new I will have to get modified again for the nose cone pickup and torque tab.

[rock]

Make sure you get a seal kit before re-assembling. Water in that area is usually due to a bad seal in the water pump base.

Rock

[tristanlee85]

Make sure you get a seal kit before re-assembling. Water in that area is usually due to a bad seal in the water pump base.

Rock

yep, thanks for the reminder. I went ahead and ordered a whole new seal kit, water pump kit, and bearings obviously.

[tristanlee85]

Can someone help me identify what is holding back the drive shaft? I have the pinion nut removed. The prop shaft is still in there - unsure if I really need to remove that though it would make reinstalling the pinion nut much easier.

I got the remains of the bearing removed, but the shaft won't pull out. I can't tell if there is still part of the bear race down there or if that is the lubrication sleeve?

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[Dave S]

beat it with a hammer.....not for the faint of heart.......Sideways slammmm....

[rock]

That pinion has been there a while and usually they don't come off without a little hand to hand combat.

Rock

[tristanlee85]

What should have been a relatively easy fix today is turning into a pain, as it always goes. I got the new tapered roller bearing pressed onto the shaft. As I am sliding the shaft back in the install the pinion, of course it hit the lower pinion bearing and knocked all the rollers out. Now I did order a new pinion roller bearing just in case, but my existing was still good so I was going to just use it... until I knocked everything out.

It looks like that bearing presses out through bottom and comes out the prop hole. In some videos, I have seen where the bearings come up through the shaft column. I don't think this one comes up because there appears to be a lip preventing that. I also can't find any online manuals and a factory one plus special tools at this point is going to be more expensive than just taking it to a shop.

I am also thinking about packing that bearing race and the rollers themselves with bearing grease or petroleum jelly and refitting them back in, though that is probably a very tedious task.

[flabum1017]

It's really not that hard to do, just look at the rollers and see if you can see a pattern on the rollers and bearing race to put them back in the original orientation (top and bottom). It's not mandatory, but if you can see the pattern, the better. This way, they roll in the original direction.

[tristanlee85]

Thanks everyone, again. Got the LU reassembled and got it out today and it runs better than ever. Still the RPMs are a little slow to climb when hammering it from a hole shot but once it finally spins up it is up on plane real quick and runs great. Still not sure why the slight hesitation from the start but still feels like a brand new boat compared to the last couple years.