Merc 30l cylinder head problems

"Hi all
my merc 3.0l starts a

"Hi all
my merc 3.0l starts and runs fine for about a minute, then starts getting more and more unhappy, oil appears in the cooling water, lots of smoke (running on muffs), then just dies when the throttle is closed.
Can't see anything obviously wrong-have rebuilt the head with new valve springs and recut the valves, still the same.
Looking inside the water jacket there is LOTS of corrosion-both the manifold and riser corroded through this year, the inside of the head looks the same-what's the likelihood the head itself has corroded through into the oil galleries/ports? Anyone heard of this?
Interested to hear your opinions."

"How much oil in the cooling w

"How much oil in the cooling water? Is your oil level going down?

Inside of the block castings often look pretty craggy, btw.

"starts and runs fine for about a minute, then starts getting more and more unhappy" and "smoke"

This sounds like a choke adjusted too far in the closed position. Smoke would be black. What happens when you push open the choke when it becomes "unhappy"?"

Is it engine oil or power stee

Is it engine oil or power steering fluid? Coolers could be shot.

""How much oil in the cool

""How much oil in the cooling water? Is your oil level going down?"
There is enough to leave a slick on the concrete behind the boat. No noticeable difference in the oil level, but it's only run for a matter of minutes.
Never occurred to me to look at the choke...
Doesn't have power steering."

"both the manifold and ris

"both the manifold and riser corroded through this year"

I assume that these were replaced?? There is a chance that you have more than 1 problem here. Check the exhaust shutter to make sure its not stuck shut for some reason. The running scenario that you describe sounds exactly like a blocked exhaust. The oil issue may be something totally unrelated.

Wrench

"exhaust shutter? do i have on

"exhaust shutter? do i have one?
yes, manifold and riser replaced, but only after large ingress of salt water and lots of surface corrosion...wondering if the hydraulic valve lifters might be sticking?forgot to say, on strip down #1 exhaust valve was dripping with oil....?"

""#1 exhaust valve was dri

""#1 exhaust valve was dripping with oil....?"

Hmmm... when you did that head job, did you change the valve seals?, Check valve guide wear? That thing has to be sucking oil there somehow. Possible that the head has a crack there. Was it magnafluxed? Pull the rocker cover off and clean the area around that valve. Clean it really good. Use varsol on a rag. Use carb cleaner. Fill that cyl. with compressed air (through the spark plug hole)(to hold the valves up) and pull that spring off the valve. Check to see if there is any oil bubbling up through a crack in the area of the valve guide. Do a CSI with a flashlight and get right in there. Look really close as there may not be much and it could be pretty tough to see. Those new valve springs should be able to push those lifters back down into their holes. The lifters would have to have zero oil on them to stick that bad.
I'm still thinking about a plugged exhaust. I may be wrong but I'm pretty sure you will have an exhaust shutter.

Wrench"

"OK, I'm getting nowhere h

"OK, I'm getting nowhere here guys.
Seems that the oil is getting into 1,3+4 cylinders through the inlet valves-those three pistons are wet with oil, the #1 exhaust valve had a large drop of oil on it when I pulled the head off...the inlet valve stems are oily...
but can't find anything obviously wrong-cylinder head is straight, no cracks found, no blocked oilways, valve lifters all fine, valve stem guides not excessively worn (no observable play on the valves)..
It appears to be sucking enough oil into the cylinders to kill combustion, but with no obvious source.
"

"Check the breather tube to se

"Check the breather tube to see if it is getting a lot of oil in it. Too much oil in the engine will be blown out the easiest opening by crankcase pressure.

But, it sounds like bad valve stem seals as wrench stated. Also, if oil is not draining from the valve train back into the block then it will fill the valve cover and force the oil into the cylinders by the valve guides if a little worn. Causes: plugged returns, wrong head gasket blocking one or more returns. Run a stiff wire down the retuns and see if it goes thru easily and comes back clean or hits an obstruction like a piece of old gasket."

"I know what you're saying

"I know what you're saying Guy, but can't see it.
First off, this engine doesn't have valve stem seals, and the oil would have to be an inch deep to be forced back down the guides...
There's no sign of oil in the carb throat or the inlet manifold, the inlet valve stems are wet, but the guides aren't worn...
At the moment all I can think to do is either-
1, put it back together-again-and see,or
2,buy a recon head on the offchance that there's something I'm missing...
I'm baffled."

"[b]"First off, this engin

""First off, this engine doesn't have valve stem seals,"

Ayuh,... It's Supposed Too....

Who rebuilt the head for you,..??"

"I rebuilt the head.
The valv

"I rebuilt the head.
The valves have small rubber o-rings at the top of the stem where the collets are (renewed), but no seals on the guides. No idea why it's arranged like that, but that is how it is."

"Typically chevy's are lik

"Typically chevy's are like that, they only have the o ring at the top of the valve stem. Put some soft rubber umbrella style seals on there that pressure fit onto the top of the valve guide. Don't use the hard plastic ones. Ford Tempo/Topaz 2.3 liter seals work perfectly on other chevy motors, they may work on yours.

Wrench"

"[b]"First off, this engin

""First off, this engine doesn't have valve stem seals, and the oil would have to be an inch deep to be forced back down the guides...
Seems that the oil is getting into 1,3+4 cylinders through the inlet valves-those three pistons are wet with oil, the #1 exhaust valve had a large drop of oil on it when I pulled the head off...the inlet valve stems are oily...
the inlet valve stems are wet,"

Ayuh,... That's because the oil is being Sucked past where the valve Seals belong....

Chevy has been using Umbrella Seals since Christ was a Pup...

If you have No Valve Seals,... They're gonna Leak,... Plain,+ Simple...


"It appears to be sucking enough oil into the cylinders to kill combustion,"

I find That hard to believe....
I'd sooner think you're trying to resurrect a Dead Horse, that's Rotted out,+ has Carb Issues, leading to the runability issues...."

"If you can point out the valv

"If you can point out the valve stem seals to me in this picture, I'll gladly buy them...
http://www.dougrussell.com/partscatalog/components/index.cfm?fuseaction=viewpart s&colid=04&coldesc=3%2E0L%2FLX%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%2 0%20%20%20%20GM%20181%20I%2FL4%201990%2D1995&index=1604&block=21&BlockNumberList =7,6,5,27,13,14,9,23,22,21,10,19,11,16,15,17,20,26,12,24,25,18,2,3,4,1,8
ooops, sorry 'bout the size of the link!
not items 14-I have renewed them..
Carb issues? A possibility-but have to rebuild to find out.."

"Ayuh,....

Your link ain&#3

"Ayuh,....

Your link ain't working for me,...
This is just from a quick google search for valve seals,+ is Only a picture of what Chevy valve seals generally look like...
http://www.valveseal.com/images/218.jpg""

"I've seen plenty of chevy

"I've seen plenty of chevy engines that only have that #14 valve seal on the valves. Get something like what Bondo is showing you, that will stop the oil from going down those guides.

Wrench"

"Sorry guys-one quite signific

"Sorry guys-one quite significant detail I've omitted from all previous posts-two weeks or less before producing the symptoms described in my first post here, she was running like a dream, smooth and sweet, temps and pressure perfect, idling sweetly,starting perfectly....
put on the trailer and returned home, then 10 or so days later I fired her up on the muffs before comitting myself to the tow to the slipway, and this problem manifested itself.
So, it's not a gradual thing, is what I'm saying.
something happened!"

"[b]"Sorry guys-one quite

""Sorry guys-one quite significant detail I've omitted from all previous posts-
So, it's not a gradual thing, is what I'm saying.
something happened!"

Ayuh,.... Like I said above,...
"I'd sooner think you're trying to resurrect a Dead Horse, that's Rotted out"

Maybe some basic Diagnostic procedures are in order....
Like a Compression Test,+ a Leak-down Test....
Then,....I'd also do a Cooling System Pressure Test..."

"Hi guys, back again with the

"Hi guys, back again with the latest.
Decided to put it back together again, as couldn't find anything wrong with the head, apart from the valve guides are a bit worn,which is probably where the oil is coming from, but not what is causing the bad running-convinced myself it must be the auto-choke!
Well, the auto-choke doesn't work at all, let alone stick in the closed position, so on first start-up yesterday, that was that one ruled out.
Let me describe exactly what happened.
All put back together, on muffs. Left the hose clamps where the exhaust riser joins the downpipe loose.
Started up, choke wide open.
Fires up, runs smoothly at fast tickover.
About 1 minute later, water starts blowing out of the exhaust riser/downpipe joint, and she starts running rough-same as before.
Switch off.
Disconnect exhaust bellows from outdrive.
Start up-runs smoothly (and loudly) for 5+ minutes (same as before the stripdown)
Today.
Stripped exhaust to check flap valve-appears to be ok, but remove it completely for testing purposes, reassemble exhaust leaving top clamps loose as yesterday.
Start up.
You guessed-1 minute or so, water starts blowing from riser joint, starts running rough, gets worse and worse, shut down.
Fetch carb cleaner spray, start up again, starts and runs fine, squirt cleaner in the carb, continues to run...and run...and run...
Going to go and reconnect exhaust bellows shortly, and no doubt after that she will be fine...until the next cold start-up...
I'm baffled, completely!"

Blockage in the bottom of the

Blockage in the bottom of the downpipe? Mouse nest?

"[b]Blockage in the bottom of

"Blockage in the bottom of the downpipe? Mouse nest?

no mate, completely clear"

"[b]Maybe some basic Diagnosti

"Maybe some basic Diagnostic procedures are in order....
Like a Compression Test,+ a Leak-down Test....
Then,....I'd also do a Cooling System Pressure Test...

What more can I say,..??...."

"Did you have the head pressur

"Did you have the head pressure checked while you had it off? This would tell you if you have issues with it.If you have it back on ,you should be able to pressure check the cooling system if its a closed system type. Keep us posted with what you find TURBOMAN"