ATF in carb to test for blown head

[StinkinRenken85]

Hey y’all mecruiser 3.0 with carb just rebuilt because of flooding issue...noticed my oil looks grey...had some leak into the bilge think it’s from the rear seal.. actually way pretty far toward in the bilge though...I saw a video online where they poured atf in the carb to show a blown head gasket and smoke cane pouring out the manifold joint...would y’all recommend this test?

 

[alldodge]

Guess I could use a bit more to clarify what is happening

.noticed my oil looks grey...had some leak into the bilge think it’s from the rear seal

You have gray oil leaking into the bilge, and it could be from the real seal?
I don't see oil being gray from much of anything leaking into the oil pan

poured atf in the carb to show a blown head gasket and smoke cane pouring out the manifold joint.

The ATF will cause it to smoke, but how is smoke coming from the manifold joint show that there is a head gasket leak?

 

[Bt Doctur]

if it leaked from the rear seal then water could enter from the rear main and contaminate he oil. did you have a high bilge? Headgaskets dont usually blow unless the motor was severely overheated, was yours?

 

[StinkinRenken85]

I’m sorry here’s the link to where I saw them supposedly checking for a blown head by pouring the atf I was just looking for a way to know if I have this problem before pulling it all apart...https://m.youtube.com/watch?v=8oAY8eVO5lE
i have been working on getting this boat going for a year when I bought it I had it on muffs but the manifolds were all rusted out and I think I over heated it it had probably been over heated before I got it too most likely... I had some white smoke and my temp said 200 or more. Water was mixed with oil and cane out the breather on valve cover. I replaced all the exhaust components manifold elbow circulating water pump impeller j pipe water shutters changed the oil a couple times and then had issues starting so changed to pertronix electronic ignition then pulled motor forward and changed the coupler cuz that was blown. Ran the boat and found it was leaking tore down the transom assembly and had a hole the gimbal housing which seems to be fixed after I patched it with fiberglass. Carb was flooding rebuilt the carb and timing was off my neighbor timed the engine said before it was running on 2 cylinders so ran the boat again and no water leak ran really well but had issues with engine dying when put in gear when not warmed up trying to move it from the dock to the trailer...had issue docking where engine died putting it in neutral after being in gear...think this is all shift cable issues but found grey oil in the bilge and grey oil on the dipstick I am thinking maybe I’m getting water intrusion still...? I think I may also have more power loss on trailer vs in water than I thought I would..and after I ran it and shut down at the dock I think I had to turn idle speed up more...maybe that’s because I was trying to get it not to die going in gear...when I ran it on muffs after the outing I was at like 2200 rpm but was only around 1000 in the water...oh yeah other than that when I ran it it ran fast didn’t overheat a little hesitation between 3/4 and full throttle though...

 

[StinkinRenken85]

But maybe the water did come in the rear seal when it was leaking on the outing before this one because there was water in the bilge then...just not now since I fixed the leak.. I haven’t changed the oil since then the pump came on many times but don’t think it ever came up to the height of the motor though...

 

[StinkinRenken85]

Also maybe I’m assuming it’s coming from the rear seal I just think that area was a little oily and I found the grey oil sitting more fowardin the bilge so maybe that’s not where it is leaking I have never seen it leak before and have ran it a lot on the trailer only in the water 3 times and this is the only time I didn’t have a water leak and found the oil...

 

[alldodge]

I'm no Miss Grammar but that was sure hard to read.

Water was mixed with oil and cane out the breather on valve cover

This is blow by and caused by piston rings

ran really well but had issues with engine dying when put in gear when not warmed up trying to move it from the dock to the trailer...had issue docking where engine died putting it in neutral after being in gear.

Dying when going into gear when not warmed up is either carb or a worm out motor without much compression. Suggest doing a compression test

Dying when going out of gear is the shift interrupter, carb, weak motor or cable adjustment. Do compression first then adjust cable/switch

I think I may also have more power loss on trailer vs in water than I thought I would..and after I ran it and shut down at the dock I think I had to turn idle speed up more...maybe that’s because I was trying to get it not to die going in gear.

Do not agree, you don't have enough power and this is why your having trouble

when I ran it on muffs after the outing I was at like 2200 rpm but was only around 1000 in the water...oh yeah other than that when I ran it it ran fast didn’t overheat a little hesitation between 3/4 and full throttle though...

2200 rpm on muffs can burn your impeller up, keep it under 1500 rpm

The hesitation is carb or weak motor

 

[StinkinRenken85]

Sorry about the grammar just trying to get it all out quick off my phone while I still have y’all attention. The engine has no hesitation when it’s not under load, just in the water. Does that make a difference? I think my compression numbers last I checked were 140 140 120 120 but I didn’t have the throttle wide open... also I adjusted the idle while the cable was on and think that the return to idle after going in and out of gear is effected by my bad adjustments... Maybe the wear in the shift cable could have caused the motor to die going in gear or bad adjustments? I know on the trailer if I have the barrel turned too far in or out it will die when I try to go in gear in coward or reverse depending on which way I turned the barrel...I will check compression again the correct way...so pouring atf down my newly rebuilt carb isn’t going to magically tell me if I have a blown head gasket then...

 

[StinkinRenken85]

And thank you for your help I do appreciate it even though right now it hasn’t been much of what I wanted to hear..

 

[alldodge]

The engine has no hesitation when it’s not under load, just in the water. Does that make a difference?

Yes, it needs good compression to be able to develop power. Low compression means it will rev in neutral or out of the water, but is not able to burn fuel efficiently to develop power. If your compression numbers are correct then your good, and then it goes back to timing and carb

Maybe the wear in the shift cable could have caused the motor to die going in gear or bad adjustments?

The shift interrupter should only effect the motor when IN the water and shifting OUT of gear.

on the trailer if I have the barrel turned too far in or out it will die when I try to go in gear in coward or reverse depending on which way I turned the barrel...I

This should have no effect on if it dies unless the throttle stop screw on the carb is not adjusted correctly and allowing the idle speed to drop below preset. Now if the carb idle circuits are still clogged then there are still more work needs to be done

so pouring atf down my newly rebuilt carb isn’t going to magically tell me if I have a blown head gasket then...

correct

 

[StinkinRenken85]

Well thanks dodge...I was able to run at full throttle I just had to punch it going between 3/4 and full otherwise it would start to bog...I will check compression again this weekend and adjust the stop screw I am pretty sure that is one of my problems ...thanks again I’m trying to learn how this whole system works...I guess I’ll just change my oil and see if it turns grey again and look for the leak as far as that part goes...really thought I had all the problems worked out until I returned to the dock and dropped out of gear...not a lot of fun losing power trying to dock around all these nice boats in FtL going to stay on the trailer in the water next time I try to test this stuff.