Merc 170 Clogged Riser = water in oil? please Help

[jake1z]

Pictures will be up shortly.... Been having a problem with my 86 170/470 engine... when i bought it it seemed to run fine. then the back heat exchanger cap got eaten through ... changed front/rear gaskets and caps. put the boat back in the water and realize i now have milky oil.. the boat would start but doesnt run well and wont start if its turned off then back on... was told it could be a cracked riser causing water to get back into cyclinders cause it to vaper lock.

took the riser off today and found the passage going to the raw water is clogged up with trust and other debris... and the inside of the riser is just a mess... question is could the clogged port have cause my heat exchanger cap to force its way over the screw and in turn some how end up putting aw water in the oil since im not missing any coolant.? sorry this is so long.

 

[mdlee]

Re: Merc 170 Clogged Riser = water in oil? please Help

I hate to say this, but is sounds like you have overheated the motor and, blown the head gasket. Water in the oil is almost a 99% indicator that the head gasket has failed. Worse is the fact that the head or, aluminum open plane on the motor may have been warped in the process.

 

[jake1z]

Re: Merc 170 Clogged Riser = water in oil? please Help

ya but that would cause it to be missing coolant. the boat is freshwater cooled and the salt water only sees the heat exchanger and riser... there isnt any coolant missing so im thinking its not the head gasket. some one else told me it could possibly be a problem/leak/crack with the raw water pump causing water to mix with the oil?

 

[mdlee]

Re: Merc 170 Clogged Riser = water in oil? please Help

The only way water can contaminate the oil is through the block or the head gasket,, You may have raw water leaking into the fresh water loop, but for it to get into the oil it has to come from the internal water cavity in the motor.

 

[nola mike]

Re: Merc 170 Clogged Riser = water in oil? please Help

The only way water can contaminate the oil is through the block or the head gasket,, You may have raw water leaking into the fresh water loop, but for it to get into the oil it has to come from the internal water cavity in the motor.

Not true. These engines are 'famous' for leaking at the cam shaft seal at the water pump, allowing coolant to mix with the oil--doesnt take a lot of water to milk-ify oil. Plenty of info with a search.

 

[mdlee]

Re: Merc 170 Clogged Riser = water in oil? please Help

Not true. These engines are 'famous' for leaking at the cam shaft seal at the water pump, allowing coolant to mix with the oil--doesnt take a lot of water to milk-ify oil. Plenty of info with a search.

And this water comes form the Block... Right?

 

[nola mike]

Re: Merc 170 Clogged Riser = water in oil? please Help

And this water comes form the Block... Right?

No, from the water pump.

 

[mdlee]

Re: Merc 170 Clogged Riser = water in oil? please Help

the pump pumps water through the ..............??????? Block....

 

[jake1z]

Re: Merc 170 Clogged Riser = water in oil? please Help

raw water at the cam shaft seals? its not the fresh water its full and clean being that i just took the thermostat out

 

[nola mike]

Re: Merc 170 Clogged Riser = water in oil? please Help

the pump pumps water through the ..............??????? Block....

Not sure what you're trying to prove here. Yes, it pumps through the block, but the leak is at the pump. No, the leak is not from within the block. No, the leak is not from an internal water passage. You claimed that 99% of the time water in oil = HG, which is wrong. This is another possibility (strong possibility in this engine). OP, you'd be losing coolant through that seal, not raw sea water.

 

[mdlee]

Re: Merc 170 Clogged Riser = water in oil? please Help

I think you have totally missed the point that he thinks that raw water in getting into the oil,,,, witch is located in the block.... just FYI. In order for water to be introduced into the oil, it has to be getting into the crankcase... thus through the block or something directly attached to the block. He has had problems with the heat exchanger..... Common sense should tell you that if the heat exchanger is bad than the motor probably has been run hot.. I don't think the seal on the water pump has any thing 2 do with the heat exchanger... Did you read the original post? The pic you posted Shows the raw and Fresh water loop... If you take a look at it you will see that raw water from the heat exchanger has nothing 2 do with the FRESH water pump.

 

[jake1z]

Re: Merc 170 Clogged Riser = water in oil? please Help

im thinking the riser being clogged caused the water to build up and push the some what corroded cap over/through the bolt holding it in place... that could explain the heat exchanger problem but the raw water getting into the oil is up in the air... im going to do a compression check for the hell of it... i need to find a picture of a riser where the raw water gets dumped in, to see if i just broke through rust or the riser housing it self

 

[mdlee]

Re: Merc 170 Clogged Riser = water in oil? please Help

Check out the Adults only post at the top of this forum, there is a full down loadable shop manual with schematics. The raw water dumps into the riser through an inlet on the port side of the riser and is expelled down the exhaust tube kinda venture like

 

[jake1z]

Re: Merc 170 Clogged Riser = water in oil? please Help

i downloaded the manual before they took them down i know where it dumps in but mine was so clogged up im not sure what its supposed to look like im trying to get the pics off my phone

 

[Don S]

Re: Merc 170 Clogged Riser = water in oil? please Help

im thinking the riser being clogged caused the water to build up and push the some what corroded cap over/through the bolt holding it in place...

Not going to happen, sorry.

When the riser plugs up, water from the raw water side of the cooling system does not flow THROUGH the heat exchanger to cool the closed cooling side (antifreeze side). It will not back up into the oil or the cylinders. It just dead ends, does not move and the engine overheats.

 

[jake1z]

Re: Merc 170 Clogged Riser = water in oil? please Help

great... to get this riser issue fixed - can the water just dump right into the riser or does it need to enter it a certain way? mine was clogged up and a punch a hole through all the muck and now water can get into the riser. i just bought this boat three weeks ago and i have it back up for sale... i really sdont want to spend 200 bucks on a new riser if this one will work now that a punched a hole in it

 

[jake1z]

Re: Merc 170 Clogged Riser = water in oil? please Help

and if the raw water stopped flowing altogether any idea where its getting into the oil at?

 

[jake1z]

Re: Merc 170 Clogged Riser = water in oil? please Help

this is the hole that was clogged that i stuck a flat head through this had the 90 degree fitting on it attached to a tube that went to the heat exchanger

 

[Don S]

Re: Merc 170 Clogged Riser = water in oil? please Help

Head gasket and cam seal are the two most common places. You need to replace the riser, cleaning only gives it a chance to destroy your engine.

Drain the antifreeze side of the engine an pressure check the cooling system, you may be able to hear where the leak is.

Check your PM's (Private Messages)

 

[mdlee]

Re: Merc 170 Clogged Riser = water in oil? please Help

and if the raw water stopped flowing altogether any idea where its getting into the oil at?

Like Don said the bad riser will cause the motor to over heat... I do think it would be worth it to pull the head and check the gasket-- If you feel comfortable doing so--. I had the same problem with one of my twin 470s. It is a little labor intensive, but you would not want to run the boat if this is possibly the problem. It is very unlikely that raw water is getting into oil, it would have to first get into the fresh water system.... then into the crankcase