"Proxy" wrote in message
.rogers.com...
1. The oil is not clear but rather milky. The oil level is much higher
then
it should be - about 2 inches on a dipstick higher then "full". This is
the
first oil after reviving the engine (see below) so I'm not sure whether to
attribute milkiness to water leftovers or blown gasket. the oil level
though
is something new.

The milky color is due to water in the oil. If the oil level is rising on
its own that is a clear indication that you are still getting water into the
oil.


4. there is rust in the intake below carb, there is also a rust streak
from
s. plug no.4 downwards indicating the water could have been leaking from
this plug socket

I would not expect water to leak out of a plug socket. If you have any
appreciable amount of water in the cylinder it would hydrolock.

5. I bought this boat with a seized engine, I soaked it, unseized, ran it
several times (never on water), starts and runs OK.

Okay, that changes my previous recommendations!


When I unseized it I
cranked out lot of water from the cylinders (min. 1 liter).

How long had the engine been sitting with water in it?

What baffles me is that except for compression test (unexpectedly high)

I thought that the compression was rather high also. Could this be a "high
performance" engine, which could have a high compression ratio (and thus
require 91 octane gas)???

If you tested the compression right after you got it to turn over for the
first time then there is a possibility that you still had some water in the
cylinders. This would certainly raise the compression numbers. If you
haven't tested it since you actually had it running you might want to do it
again.

I have all indications of blown head gasket.

A head gasket can fail in several ways. The gasket must seal the cylinder
pressure. There are also water passages that are under moderate pressure (a
few PSI on a boat engine, up to 14 PSI on a closed cooling system). There
are also oil passages that are not under pressure.

A common failure is to have the pressure from the cylinder rupture the
gasket. The rupture can go to the outside, an oil passage, or the water
jacket. Such a rupture should show up on a compression test. Other than
that, a rupture to the outside might not be noticable. A rupture to the
water jacket would cause overheating on a closed cooling system but might be
unnoticable on a boat with raw water cooling unless water entered the
cylinder when the engine cooled. A rupture to an oil passage would result
in excessive amount of "blow by".

It is also possible for the water jacket to seal to fail, either to the
outside or to an oil passage. To the outside would result in a visible leak,
while a ruptuer to the oil passage would cause your crankcase to fill with
water. Since the cylinder is still sealed this failure will not show up on
a compression test. Usually, this sort of failure is the result of a warped
head, perhaps the result of overheating. If the head is warped, just
replacing the gasket may not fix the problem.

I would recommend removing the heads and examining them. This, of course,
requires removal of both the intake and exhaust manifolds, which it sounds
like you may have already done once. Generally, once you have the manifolds
off getting the heads off isn't too difficult. This will also allow you to
examine the cylinders to see if there is any rust issues inside.

Rod

OK, changed the oil today, pumped out 9 liters ! of sludge, some of it so
thick that I couldn't believe my eyes. As indicated I have not had the boat
in the water yet (no time plus a big "?" with regard to the engine). Oil
filter contained almost no oil but water. I ran the engine last year on the
hose for about 20 min altogether. That was after putting new oil in the
engine (first change after getting it to run).
Considering short time that I had it running on the hose it seems like I
have a major leak. Since compression is quite high (140-160) I wonder
whether it is something else other then head gasket (cracked block?). Water
seems to accumulate in crackcase although as I said looks like also in cyl.
# 4. I ran the engine today for about 30 sec. (dry, no water). Seems to be
working, This a regular 305 8cyl. 5L OMC engine, nothing special about it.
I guess there is no way to avoid heads removal. I bought Block Seal (K&W
product) after I read some really good comments about it (many swar by it).
I planned to connect 2 exhaust water hoses (that are normally hooked to
manifolds) together and connect them with water inlet hose (unhook from the
outdrive - bell housing) thereby creating a loop. I planned to fill it with
water mixed with Block Seal and run it for 5 min. That should help seal
small cracks (wonder how small or big mine is). If no improvement I would
remove heads. In theory my plan looks OK but God knows.... Considering what
I've accomplished so far without taking the engine apart I'm still
optimistic although prospects are quite tough. What do you think should I
do? What is the most likely fault/damage here?





"Rod McInnis" wrote in message
...

"Proxy" wrote in message
.rogers.com...
1. The oil is not clear but rather milky. The oil level is much higher
then
it should be - about 2 inches on a dipstick higher then "full". This is
the
first oil after reviving the engine (see below) so I'm not sure whether
to
attribute milkiness to water leftovers or blown gasket. the oil level
though
is something new.

The milky color is due to water in the oil. If the oil level is rising on
its own that is a clear indication that you are still getting water into
the
oil.


4. there is rust in the intake below carb, there is also a rust streak
from
s. plug no.4 downwards indicating the water could have been leaking from
this plug socket

I would not expect water to leak out of a plug socket. If you have any
appreciable amount of water in the cylinder it would hydrolock.

5. I bought this boat with a seized engine, I soaked it, unseized, ran
it
several times (never on water), starts and runs OK.

Okay, that changes my previous recommendations!


When I unseized it I
cranked out lot of water from the cylinders (min. 1 liter).

How long had the engine been sitting with water in it?

What baffles me is that except for compression test (unexpectedly high)

I thought that the compression was rather high also. Could this be a
"high
performance" engine, which could have a high compression ratio (and thus
require 91 octane gas)???

If you tested the compression right after you got it to turn over for the
first time then there is a possibility that you still had some water in
the
cylinders. This would certainly raise the compression numbers. If you
haven't tested it since you actually had it running you might want to do
it
again.

I have all indications of blown head gasket.

A head gasket can fail in several ways. The gasket must seal the cylinder
pressure. There are also water passages that are under moderate pressure
(a
few PSI on a boat engine, up to 14 PSI on a closed cooling system). There
are also oil passages that are not under pressure.

A common failure is to have the pressure from the cylinder rupture the
gasket. The rupture can go to the outside, an oil passage, or the water
jacket. Such a rupture should show up on a compression test. Other than
that, a rupture to the outside might not be noticable. A rupture to the
water jacket would cause overheating on a closed cooling system but might
be
unnoticable on a boat with raw water cooling unless water entered the
cylinder when the engine cooled. A rupture to an oil passage would result
in excessive amount of "blow by".

It is also possible for the water jacket to seal to fail, either to the
outside or to an oil passage. To the outside would result in a visible
leak,
while a ruptuer to the oil passage would cause your crankcase to fill with
water. Since the cylinder is still sealed this failure will not show up
on
a compression test. Usually, this sort of failure is the result of a
warped
head, perhaps the result of overheating. If the head is warped, just
replacing the gasket may not fix the problem.

I would recommend removing the heads and examining them. This, of course,
requires removal of both the intake and exhaust manifolds, which it sounds
like you may have already done once. Generally, once you have the
manifolds
off getting the heads off isn't too difficult. This will also allow you
to
examine the cylinders to see if there is any rust issues inside.

Rod