Coolant on piston 97 F150 4.6L

corys46 · #1 (**permalink**) 03-29-2008, 05:36 PM

OK,where do I start The motor misses,does not show on live codes. new plugs,Then found coolant on some pistons.Can this be the Intake gasket?

corys46 · #2 (**permalink**) 03-29-2008, 06:55 PM

BTW tested compression,wet It's up and down;80-120 took a few tries for #7 to show a reading suspect a sticky valve.

I actually stuck a rag into the c-chamber and it came up with coolant on it.
Also,smell of combustion in the coolant tank and coolant smell out the exhaust
Oil was a bit brown,so I changed it

Going to try pressurizing the coolant.
286000kms on the beast(129000mi) My next move is Gunk block sealer,then a used motor,before I get too much into this one.

Any advice would be appreciated.

LxMan1 · #3 (**permalink**) 03-30-2008, 12:43 AM

Welcome to the forum

Sounds like either a blown head gasket or cracked head to me.

corys46 · #4 (**permalink**) 03-30-2008, 07:15 AM

Thank you

I've heard some rumor about intake gasket problems.
How do I test for that?

I've got an air ratchet and I'm not afraid to use it!

LxMan1 · #5 (**permalink**) 03-30-2008, 06:07 PM

Pressure testing the cooling system should help pinpoint the leak. Usually if it is an intake problem, it will leak in the front, not near cyl 7.

corys46 · #6 (**permalink**) 03-30-2008, 08:41 PM

I found the most coolant in #1

So far,I've drained the coolant and filled with water twice,running the engine each time until t-stat opened.removed the lower hose and flushed thoroughly.Coolant is still coming out brown.

There is a lot of sediment in this system. Also when the initial problem occurred,Green coolant was added,about 5 months ago,then the truck sat for a while...
With the rad cap off,the motor didn't seem to miss as much.

I pulled off the 3/8" line from the top of the coolant tank and stuck it under the coolant level through the rad cap hole;it bubbled steady with the motor running.Is this from combustion gas?

It will overflow the coolant if I leave the cap off long enough with the motor running

LxMan1 · #7 (**permalink**) 03-31-2008, 12:17 AM

Sounds like a head gasket.
you need to put the cylinder up on top dead center so that both valves are closed and put compressed air into the cylinder ( I use a compression tester hose with the shrader valve insert removed) and see if you get bubbling in your coolant overflow. If so, the heads need to come off.

corys46 · #8 (**permalink**) 03-31-2008, 07:29 PM

Thanks I'll give it a try.Playing Mr mom tonight!

corys46 · #9 (**permalink**) 04-08-2008, 05:46 PM

I've been running Gunk and water in the rad for a week now.Seems to have stopped leaking

Also found a cam follower had come off,when I opened the rocker cover found about 1/2" of sludge under it.flushed the crankase with a quart of diesel,then dropped the oil.(only abot 80 miles on it)Came out real black

Now my oil pressure guage stopped fluctuating too,must have loosened up the crap in that sensor too.

Thanks again LX MAN1 You've been a great help!

LxMan1 · #10 (**permalink**) 04-08-2008, 10:25 PM

Good luck

Ladyfire3374 · #11 (**permalink**) 04-30-2008, 01:47 PM

LX,
I have a 4.6, 160k mi, had an overheat incident due to leaky radiator & inexperienced driver. Replaced radiator & t-stat, (fresh coolant but no flush), coolant still leaking, temp still heads into the hot zone on warmer days.

I travel for work now & don't do as much of my own work as I used to. :-(
My mechanic says he did a "block test" and found exhaust in the coolant, which is very dark and smells somewhat of exhaust.

It was hesitating a lot til it warmed up, but I took off the reservoir cap and let the coolant bubble back into the reservoir (glub, glub). The hesitation hasn't happened since. Later that day, I also added some stop-leak.

Is this definitively a cracked head/block/blown gasket or is it worth my time to look for an intake gasket leak?

krewat · #12 (**permalink**) 05-01-2008, 10:39 AM

Sounds like combustion pressure is getting back into the cooling system - bad head gasket, cracked head, cracked cylinder, etc.

BUT - one thing to look out for, is the plastic intake might have cracked internally and is pushing coolant into the cylinder. But by now, it's probably hydrolocked anyway.

Pressure check the system.

Ladyfire3374 · #13 (**permalink**) 05-04-2008, 07:22 PM

Krewat,

Thanks for the timely reply.

Two questions:
What is hydrolocking?

How do I do a pressure test? Do I need to compression test to find the suspect area, then do as LX recommends below or are you thinking of something else?

krewat · #14 (**permalink**) 05-05-2008, 07:45 AM

Hydrolocking is where you get water (or some other fluid) in the cylinder, and on it's compression stroke, can't compress the liquid, so it cracks the piston, spins a rod bearing, etc. Not good.

Pressure checking the system means pressurizing the cooling system and seeing if the pressure drops, meaning there's a leak.

A compression check is where you check compression in every cylinder, if one or two are low, the head gasket is most likely leaking.