1989 Mariner 175Ski

[tlwjkw]

here it is...... get a pressure gauge!!!!!!!!!!!!!!!!!

[Glastron1987]

here it is...... get a pressure gauge!!!!!!!!!!!!!!!!!

Cool

[Glastron1987]

Or the poppet is leaking and the block can't get enough "head" pressure to fill completely.

Yeah, I think I'll make fixing that entirely a priority before another test.

[skialot2]

I think you have a blockage in the exhaust plate or in the block going from the exhaust plate to the cylinder cooling passages. Here is some pictures of how the water travels. The water goes up the water tube to the top of the block. It comes out here Then it goes into the exhaust plate here Comes out the exhaust plate and goes through these 2 sets of three little holes into the cylinder cooling passages Only the bottom 2 cylinders have the holes. Then into the top of the head past the thermostats and out the bottom. I think your problem will be with the three little holes going through the block into the cylinders. If it was a poppit problem, I don't think water would come out of either head.

[Glastron1987]

Very nice, thank you skialot2.

[Glastron1987]

I cleaned up the poppet plates with sandpaper on glass and a sanding block. There actually was one spot on one of the edges that looked suspicious and may have been causing the leaking. I ran the garden hose through the water tube to test, and it appears to be good now with no leaking.

Also, when running the garden hose through the water tube I noticed, as before, that water would come out of the port thermostat hole but not the starboard side ...until I blocked the port side. Then water would come out from the starboard side no problem. Is that normal?


Also, around the garden hose, I assume there was leakage because it was not clamped to the water tube, but there was this constant stream behind the hose coming down from the midsection. It's tough to look up there to find the source, but anyone know what that could be? Seems like that may not be normal and could be robbing the system of some volume.

[Glastron1987]

Oh, now looking at the diagram again maybe that little stream is the cooling spray into the exhaust tubes. Hope so.

[OnPad]

Could be a combo of low pressure on your hose, and leaks. I think your extra hole under the poppet cover is leaking down the dump into the mid, and the holes that skialot mentioned, also dump into mid. Not a deal breaker, but enough of a leak that merc changed the design in order to help keep the block full at idle. The port thermostat is lower than starboard, hence you only get water out of the low one, until you block it off.

I would measure all cylinders, If good, replace bad piston/s, rod bolts, rod bearing/s. put thermostats back in, install a pressure gauge, and check pressure. If you still can't keep water in engine,... block the extra hole under the poppet, or remove powerhead, clean and replace the adapter plate gaskets. If still concerned about the starboard side, a tell tale from each thermostat housing is a option.

I believe this to be where water is leaking out of the bottom of the water column. This passage runs up under the poppet diaphragm, then out the dump, or if making lots of volume it helps open the poppet (possibly)....
The later design doesn't put water here until the block is full, getting its flow from a hose where your water pressure gauge was located, then to a fitting on the poppet cover. This is also a option you could retrofit.

[Glastron1987]

Sure, if the poppet gives me any more trouble, I'll do the retrofit. Right now, it is looking good.

All cylinders except #1 look good. I'll try running one more time with a water pressure gauge applied and see what I get. Hopefully the cooling system will be OK now, then I'll proceed to break down the engine to repair that bad cylinder.

[skialot2]

You definitely need to plug the small hole in the poppet. If the small boss is open, the water is going from the intake dumping straight out the poppet. Never going through the cooling system. Put the hose on with the poppet cover off and see how much water shoots out. All that is missing the cooling system. Plugging the small hole should fix the cooling flow problem.

[pcrussell50]

You definitely need to plug the small hole in the poppet. If the small boss is open, the water is going from the intake dumping straight out the poppet. Never going through the cooling system. Put the hose on with the poppet cover off and see how much water shoots out. All that is missing the cooling system. Plugging the small hole should fix the cooling flow problem.

I can confirm this. One of my motors in this family has this “dogbone” style poppet, in which the small end is open. There is a hose barb on the small end, with a hose that joins up with the other hoses.

There is another style of poppet in this family of motors, in which the cavity for the small hole is present, but there is no opening there into the rest of the block. This kind of poppet only uses the big end. So it’s a circle instead of a dogbone.

-Peter

[Glastron1987]

The poppet isn't leaking anymore. That is good, but it looks like the exhaust system has been redesigned to exit the pee-hole. This keeps the water pressure from going to high; stays at around 1lb.

[skialot2]

The poppet isn't leaking anymore. That is good, but it looks like the exhaust system has been redesigned to exit the pee-hole. This keeps the water pressure from going to high; stays at around 1lb.

Unfortunately, you are going to have to pull the poppet cover again and plug the small side of the poppet. It is the original thermostat location. but it didn't work well so they moved the thermostats to the heads. They just left the boss there and didn't machine it for the thermostat. It needs to be plugged. It will cause a major loss of water pressure. The water from the water pump as going straight out the poppet without going through the motor.

Compression is getting into the cooling system. Probably the head gasket. I know you had the head off a couple of times. Did you replace the head gasket? They are not reuseable.

[tlwjkw]

Unfortunately, you are going to have to pull the poppet cover again and plug the small side of the poppet. It is the original thermostat location. but it didn't work well so they moved the thermostats to the heads. They just left the boss there and didn't machine it for the thermostat. It needs to be plugged. It will cause a major loss of water pressure. The water from the water pump as going straight out the poppet without going through the motor.

jus where in tha hell did you come up with this??? in your dreams??.. tha 2.0, 2.4, 2.5 has NEVER had a stat there............. not even for practice....

jan... tha few we had come thru tha shop "with that hole" and completely stock did not have any coolin' problems.. they were there for other reasons.........

[Glastron1987]

The poppet worked stock for at least a decade. I can tell because good compression ratings are written on the engine in 1999. So, I am doubting that the poppet is causing any issue right now.

The head gasket I had replaced, but yes, I did take the head off again so maybe I need to get another head gasket to try. Probably that is one advantage of the newer o-rings.