Sorry for the long post.
1979 Mercruiser 260 with aftermarket closed cooling system (half). SE 106 (alpha 1) outdrive.
Have discovered a persistant leak in my cooling system which is sending water into my oil pan - the motor has been running well, but steams and smokes a little at start-up. Once warm, it runs like a champ - cruising at 3000 rpm no smoke, no steam, runs smooth.
After loosing a gallon of coolant (about 5-6 hours run time at 3000 rpm) and not knowing where it went, I checked my oil and it was fine. Dark amber trending towards black - just like it should look. No water mixed in.
I assumed the coolant was leaking out of my overflow tank, into the bilge, and out to sea.
Several trips later (another 5-6 hours of run tim) I had to add another gallon of water to the cooling system. Oil still good - although a bit full...
After a few trips this past weekend, I popped the engine cover to check the oil and found it easy to do as there was lots of oil in my bilge. I cheked the oil again. Looks fine - but I have way too much measured on the stick and at least a few quarts in the bilge. I closed the cover and have not gone back for it - too busy at work to fix it now.
a while ago, I puzzled over (and posted) about a little coolant in my oil, but after pressure testing the system and deciding to test the engine the only way I knew how (run it and see what happens) I have now solved part of the mystery. I am leaking coolant into my oil... but from where? That's the mystery.
It seems like it's happening passively, when not under a load - otherwise the motor would be running rough and showing more sign of vapor / smoke, right? Or not?
I have guessed that I could be passing coolant at my exhaust riser block-off gasket when not running - but still warm and under pressure - causing coolant to drain into my exhaust manifold, then into my exhaust port, past the piston rings, and into my pan. This seems to explain why it steams and smokes a bit at start up, but not once idling. Although, I am a novice and could be totally wrong.
So, since I don't have access to a machine shop or marine mechanic. I have to do it myself and cannot have my heads or block checked for cracks. My plan is to just pull apart the top of the motor, replace intake, exhaust and head gaskets and see what happens. If it does it again, I will just replace with a new long block...
Which brings me to a new set of questions: I really want to replace the distributor, manifold and carb. I am leaning towards edlebrock marine for intake and carb and am wondering which one I need. Looking at performer intake mani and marin carb 750cfm. Most intake mani's only accept electric choke, which carbs also come with. How hard is it to retro from a 79 mechanical choke set-up to a later model electronic choke?
Also, if I go the route of new long block, was thinking of vortec heads for extra horses - would a performer manifold be interchangeable between different heads, or do the vortec heads require a matching manifold?
Thanks and if I don't reply right away to questions, I am sorry - I have to drop off the map for a week.
As always, thanks for all your help - you guys are incredible!
1979 Mercruiser 260 with aftermarket closed cooling system (half). SE 106 (alpha 1) outdrive.
Have discovered a persistant leak in my cooling system which is sending water into my oil pan - the motor has been running well, but steams and smokes a little at start-up. Once warm, it runs like a champ - cruising at 3000 rpm no smoke, no steam, runs smooth.
After loosing a gallon of coolant (about 5-6 hours run time at 3000 rpm) and not knowing where it went, I checked my oil and it was fine. Dark amber trending towards black - just like it should look. No water mixed in.
I assumed the coolant was leaking out of my overflow tank, into the bilge, and out to sea.
Several trips later (another 5-6 hours of run tim) I had to add another gallon of water to the cooling system. Oil still good - although a bit full...
After a few trips this past weekend, I popped the engine cover to check the oil and found it easy to do as there was lots of oil in my bilge. I cheked the oil again. Looks fine - but I have way too much measured on the stick and at least a few quarts in the bilge. I closed the cover and have not gone back for it - too busy at work to fix it now.
a while ago, I puzzled over (and posted) about a little coolant in my oil, but after pressure testing the system and deciding to test the engine the only way I knew how (run it and see what happens) I have now solved part of the mystery. I am leaking coolant into my oil... but from where? That's the mystery.
It seems like it's happening passively, when not under a load - otherwise the motor would be running rough and showing more sign of vapor / smoke, right? Or not?
I have guessed that I could be passing coolant at my exhaust riser block-off gasket when not running - but still warm and under pressure - causing coolant to drain into my exhaust manifold, then into my exhaust port, past the piston rings, and into my pan. This seems to explain why it steams and smokes a bit at start up, but not once idling. Although, I am a novice and could be totally wrong.
So, since I don't have access to a machine shop or marine mechanic. I have to do it myself and cannot have my heads or block checked for cracks. My plan is to just pull apart the top of the motor, replace intake, exhaust and head gaskets and see what happens. If it does it again, I will just replace with a new long block...
Which brings me to a new set of questions: I really want to replace the distributor, manifold and carb. I am leaning towards edlebrock marine for intake and carb and am wondering which one I need. Looking at performer intake mani and marin carb 750cfm. Most intake mani's only accept electric choke, which carbs also come with. How hard is it to retro from a 79 mechanical choke set-up to a later model electronic choke?
Also, if I go the route of new long block, was thinking of vortec heads for extra horses - would a performer manifold be interchangeable between different heads, or do the vortec heads require a matching manifold?
Thanks and if I don't reply right away to questions, I am sorry - I have to drop off the map for a week.
As always, thanks for all your help - you guys are incredible!