1989 Mariner 175Ski

[pcrussell50]

Ummmm.... Anyone ever seen a hole in the block on the little side of the poppet cavity? I've never seen the little side with a hole in the block like that. You should have water gushing out of that hole even at cranking speed, but in my mind that hole shouldn't be there, your block wouldn't fill or hold pressure correctly. Maybe someone else has some idea?

I can confirm that my late 1990 2.4/200 does not have that hole in the small cavity.

Further, I have two 2.0/150’s (1986 and 1987) and they both have the two bolt poppet with the small cavity completely uncovered. Obviously no hole in the small cavity in that case.

-Peter

[rock]

I have seen them both ways. Not real sure why but it is a factory thing.

Rock

[OnPad]

I have seen them both ways. Not real sure why but it is a factory thing.

Rock

Interesting,..... That hole would lead directly to the main water feed, before it made it to the top of block, on the 1990 engine I'm looking at.

At this point I think Glastron1987 would be wise to drop the lower again and check his work, or for any missing parts. It gets easier the more times you do it. If you can't find a helper, use a piece of wood to jam the case up (third hand) while you fiddle with water tube, driveshaft, and shifter. Leaving it in gear will allow you to spin the propshaft, helping align your driveshaft splines. When you have the l/u off you can remove the pipe plug you were asking about earlier, install a garden hose in that hole. While trimmed up, you may be able to back flush sand /gravel out the intake side of adapter plate.

A idling engine should fill to the top of both heads, (or the plug in the top of block) in about 20 seconds at the lake, probably faster on the hose with proper fitting muffs. Likely never with poorly fitting muffs. Once the engine is full it takes a few minutes for the thermostats to open.

[Glastron1987]

Nope! Not normal. I have never seen a hole on the little side. It's always plugged off. That's probably your overheating problem. Find a freeze plug that will fit and plug it.

Your motor was probably run with the blown head gasket for a while. With 40psi compression, it probably wasn't running on that cylinder at all. Probably washed out the rings a little. Maybe glazed the cylinder walls. Go for a ride if it's not overheating. With 90psi it should run on that cylinder and compression may come back after a while. If it doesn't, before rebuilding, you can try pulling the head again. Push that piston down. If the cylinder walls are smooth, put some rags in the ports and take a scotchbrite pad and lightly scrub the cylinder walls down to break the glaze. Clean it out good, Put the head back on, go for a ride. Then check compression again. You might get lucky. Be careful if you have nikasil cylinders. They are thin and easy to sand through.

I like the idea of once getting past the overheat problem taking it for a ride and seeing if compression comes back and if not take the scotchbrite to it. I'm still confused about the small hole though because Rock says he's seen them opened and blocked. Per Onpad I probably do need to take the LU off again and test that way.

[Glastron1987]

Rev it up and see how much sprays out of the fitting on top

Just a little spitting came out even when reving it.

[OnPad]

I believe Rock,... and also like the idea of blocking the little hole off, like skialot recommended. It's a leak directly down the poppet dump. Not unlike the hose from poppet cover to top of engine on later model stuff, but in a less ideal location. Maybe not enough to keep the block from filling with a operational pump, but it isn't helping. That little hole isn't far from your pump. If your having problems getting water there, you got no chance at the top of the block. We're only talking like 6 or 19 oz.of water above pump to that hole. How does a garden hose not fill the block with tight fitting muffs, properly installed (rotating) water pump and feed tube??? My guess is something isn't right in the water pump/feed, or plugged adapter plate.
The test pcrussell showed a video of is legit. Good for testing if your getting water through the block, or dislodging crud in adapter. If you were to momentarily apply water this way, then let drain, it could back flush junk out of the adapter that collects at the first low spot. Kinda the reverse of the method I mentioned a few posts back.

this is where all the pebbles and fishing sinkers get stuck between the two plates.

Was your poppet, and associated parts present?
How are you feeding the engine water, ...muffs, trough, or lake? Your muffs good n tight?

[tlwjkw]

...

I have seen them both ways. Not real sure why but it is a factory thing.

Rock

i have, as you, seen tha hole in a few motors.. jus never paid much attention to it...... sometimes ya jus gotta wonder what merc engineers were thinkin'...........

jus gonna add..
if its got tha hole then you would think tha plate/plates may be a little different maybe???

[Glastron1987]

I believe Rock,... and also like the idea of blocking the little hole off, like skialot recommended. It's a leak directly down the poppet dump. Not unlike the hose from poppet cover to top of engine on later model stuff, but in a less ideal location. Maybe not enough to keep the block from filling with a operational pump, but it isn't helping. That little hole isn't far from your pump. If your having problems getting water there, you got no chance at the top of the block. We're only talking like 6 or 19 oz.of water above pump to that hole. How does a garden hose not fill the block with tight fitting muffs, properly installed (rotating) water pump and feed tube??? My guess is something isn't right in the water pump/feed, or plugged adapter plate.
The test pcrussell showed a video of is legit. Good for testing if your getting water through the block, or dislodging crud in adapter. If you were to momentarily apply water this way, then let drain, it could back flush junk out of the adapter that collects at the first low spot. Kinda the reverse of the method I mentioned a few posts back.

this is where all the pebbles and fishing sinkers get stuck between the two plates.

Was your poppet, and associated parts present?
How are you feeding the engine water, ...muffs, trough, or lake? Your muffs good n tight?

My muffs seem to fit snuggly, but the water pressure from my hose isn't really too strong. Never observed this as an issue on other motors using my hose, but I'm wondering if that is an issue.

[rock]

Might need to dip it in the crick. I have had motors show nothing on the muff but be fine in the water. Pump and lower being submerged makes aa difference on some of them.

Rock

[Glastron1987]

Might need to dip it in the crick. I have had motors show nothing on the muff but be fine in the water. Pump and lower being submerged makes aa difference on some of them.

Rock

Interesting. Now I may mount it to the boat and try it out.

[Aaronhl]

Interesting. Now I may mount it to the boat and try it out.

Order the jack plate yet ??

[Glastron1987]

Order the jack plate yet ??

Since you're pushing me, I just ordered a 6"

[Glastron1987]

So I got the kit to replace the poppet. Should I block that small hole with a freeze plug before installing? or leave it as is? Not sure how that works.

[rock]

I would leave it alone. Merc put it here for a reason even though we can't figure out what the reason was. Pretty sure the engineers were smarter than I.

Rock

[Glastron1987]

Poppet in now. I'll start it up and see if there is any water getting to the heads.