1997 Mercruiser 5.7 EFI blown head gasket

[khe]

I dont think its the head gaskets. A leakdown test will tell

we still do not know if this is a vortec motor or a non-vortec motor.

I should be able to tell if it is a Vortec or non-Vortec this evening based on the quantity of intake bolts per Bondo's description.

At this point, I don't know if it is the headgasket, all I know is I have zero compression on two adjacent cylinders and am assuming it's a headgasket issue.

 

[stresspoint]

im going against the grain here , after having a improper sealing of a couple of sets of felpro ( been happy with them for automotive for years).
i put it down to raw water cooling varying temps too much for the gasket to seal adequately.

anyway that said , i went with OEM Mercruiser head gaskets to avoid leaking , they are glued so once heated the gooy stuff seals the motor no matter how often the temp varies.

OP , your compression numbers could be a cracked block , be sure when you pull the heads carefully so as you get a good surface reading off the block , heads and gasket mating areas.

 

[Scott06]

I'm wondering if this is just a 26 year old engine that over the years of raw water cooling has decided to puke a headgasket or is there some other underlying cause that damaged the headgasket?

I 've had several engines older than that that head gaskets were fine in. Also if you haven't owned it since new you don't know what has happened.

I think with Lou's boat he had several years in between over heat and head gasket failure.

Bottom line do a leak down or at least pressurize the combustion chamber with air before you take it apart. IF you do this when both valves are closed you can see if you get any leakage past valves

 

[Lou C]

On second thought I wonder if you might have 2 exhaust valves stuck open on those 2 cyls, maybe from leaky exhaust if you had no overheating.
yep i had the overheat in july 2013 didn't get water in cyls till end of aug 2016
however sodium (salt water cooled) showed up in an oil analysis before that showing that the leakage had started before then

 

[khe]

I made some progress this evening. I got the exhaust manifolds and the distributor removed. I also verified the valves are opening and closing on the cylinders with no compression (#3 & #5). When I put #3 at top dead center on the compression stroke and applied shop air through the #3 spark plug hole with an adapter, air was rushing out the #5 spark plug hole. I think that points to a head gasket. I would have liked to have pulled the intake manifold this evening but ran out of daylight and was too tired. I think marine mechanics earn every dollar they charge - I am beat!

My plan for tomorrow evening (if it doesn't rain...) is to remove the intake manifold, pushrods and the heads so I can get the heads to the machine shop Wednesday morning on the way to work.

The shop said they could get the job done in 5-7 business days - while the heads are at the machine shop, I'll clean up the gasket surfaces, purchase parts, etc.

 

[khe]

When I put the #1 cylinder on it's compression stroke, the notch on the balancer aligned with the feature to the right which I assume is the pointer?

 

[Scott Danforth]

When I put #3 at top dead center on the compression stroke and applied shop air through the #3 spark plug hole with an adapter, air was rushing out the #5 spark plug hole. I think that points to a head gasket.

or fire-slotted block. or cracked head

time to pull the heads

 

[Scott06]

When I put the #1 cylinder on it's compression stroke, the notch on the balancer aligned with the feature to the right which I assume is the pointer?

Assume you are asking for how to retime the engine ? Yes but u need to make sure it is on compression stroke - both valves closed as the balancer will also align at top of exhaust stroke …

 

[khe]

or fire-slotted block. or cracked head

time to pull the h

Assume you are asking for how to retime the engine ? Yes but u need to make sure it is on compression stroke - both valves closed as the balancer will also align at top of exhaust stroke …

No - I am asking if the feature in the timing cover just to the right of the slot in the balancer is the pointer. It looks like a white "U" on the curved rib on the timing cover. Usually there is a metal notched scale with the degrees before or after top dead center stamped into it. This application has the scale on the balancer itself.

 

[khe]

Non vortec motors went away September of 1995 when the vortec motors came out

Any non-vortec motor after September 1995 is a left-over old stock motor stored in a warehouse and used later

Do you have 12 intake bolts (non-vortec) or 8 intake bolts (vortec)

12 intake mounting bolts on my engine - looks like I have the non-Vortec heads. Are those less prone to cracking vs. the Vortec heads?

 

[nola mike]

No - I am asking if the feature in the timing cover just to the right of the slot in the balancer is the pointer. It looks like a white "U" on the curved rib on the timing cover. Usually there is a metal notched scale with the degrees before or after top dead center stamped into it. This application has the scale on the balancer itself.

Whoa... You're either on compression OR exhaust stroke on #1. Not necessarily on 3 and/or 5. Without looking, certainly possible you have open intake valves on those cylinders, so your test might be wrong

Edit: and yes, that's the timing mark on the composite cover

 

[stresspoint]

it really make s no difference at all at this point where the timing is.
FWIW, the mark you circled lines up with top of stroke on # 1 piston .

before you reassemble the motor bring the lifters to the correct position (compression) ,line up that mark , locate #1 lead on the distributor cap and mark the distributor with a paint pen , push the distributor in the hole with the rotor button lining to that point.
TDC #1 cylinder on compression stroke.

when you get all assemble , hook a timing light and set the timing to the correct spec with the motor running , NOTE : sometimes you need to guess advance the distributor to get the motor started as early SBC don't like to fire up easy @tdc for some reason .

 

[nola mike]

it really make s no difference at all at this point where the timing is.
FWIW, the mark you circled lines up with top of stroke on # 1 piston .

Whoops yeah you're right, compression on #1. But if he's putting air into 3 and 5 at that point their intake valves might not be closed.

 

[khe]

Whoa... You're either on compression OR exhaust stroke on #1. Not necessarily on 3 and/or 5. Without looking, certainly possible you have open intake valves on those cylinders, so your test might be wrong

Edit: and yes, that's the timing mark on the composite cover

The #1 cylinder is on the compression stroke. and the slot on the balancer aligns with the feature on the composite. I was just clarifying the feature on the timing cover.

When I did the air test on cylinder #3, cylinder #3 was at TDC with both valves closed.

 

[Scott06]

No - I am asking if the feature in the timing cover just to the right of the slot in the balancer is the pointer. It looks like a white "U" on the curved rib on the timing cover. Usually there is a metal notched scale with the degrees before or after top dead center stamped into it. This application has the scale on the balancer itself.

yes the U is the timing mark on cover.

 

[khe]

I got the intake manifold removed and the port side head removed - bad news... There's a channel burned in the web between cylinders 3 & 5 and also the head.

I talked to the machine shop that I was going to use to have the valves reconditioned and he said this is a common problem with either cylinders 2 & 4 or 3 & 5 due to the exhaust ports being right next to each other.

At this point, I need to start shopping for an engine.

 

[Scott06]

I got the intake manifold removed and the port side head removed - bad news... There's a channel burned in the web between cylinders 3 & 5 and also the head.

I talked to the machine shop that I was going to use to have the valves reconditioned and he said this is a common problem with either cylinders 2 & 4 or 3 & 5 due to the exhaust ports being right next to each other.

At this point, I need to start shopping for an engine.

try michigan motorz they have new base engines and remans. I was pleased with my engine purchase there a few years back

 

[Scott Danforth]

I got the intake manifold removed and the port side head removed - bad news... There's a channel burned in the web between cylinders 3 & 5 and also the head.

its called fire-sloting

its what happens when you run it with a bad head gasket for a bit.

I have in a pinch, welded up the fire-slot, dress the welds and run the motor. usually the head will crack in about 3 months.

if the slot is not too deep, you can surface the motor deck and get new heads.

 

[Lou C]

That’s the problem with predicting outcomes with blown HGs; it all depends on where they blow. Mine didn’t blow between cyls it leaked from a water passage.

 

[khe]

its called fire-sloting

its what happens when you run it with a bad head gasket for a bit.

I have in a pinch, welded up the fire-slot, dress the welds and run the motor. usually the head will crack in about 3 months.

if the slot is not too deep, you can surface the motor deck and get new heads.

I am shopping for a new/remanufactured engine. I do not want to go through this crap in three months or less. The slot is about .060" deep in the block and head. Strange that there were no symptoms other than some hesitation/stumbling on prior cruises before the cylinders went dead on the last trip. I am wondering if at 1500 hours on the replacement engine I need to replace the headgaskets...?

I need to figure out what vintage of engine I have - per the serial number, it is a 1997 (original to the boat and non-Vortec) but others have indicated, Sea Ray may have been using old stock. The remote oil filter lines are different on my engine vs what I look up on the Mercury parts site. My lines are leaking at the crimps and I want to fix that also.