3.0 Blowing Head Gaskets

I am looking for any ideas out there. I have a 1998 Mercruiser 3.0 181 CID. I overheated a month ago, and blew the head gasket between the 2nd and 3rd cylinders. It required a shaving of the head (the block was fine) and the replacement of four valves and the head gasket. I had to replace the water pump which was the reason for the overheat. I also rebuilt the carb, replaced the belt, the fuel lines the fuel pump and the fuel filter. I put it all back together and took it our for about four hours, never going over 50% of WOT. A week later I took it out after idling in the water for a half hour and within 5 minutes after going at 50-70% WOT, I heard a pop and took it back to the ramp. I blew the head gasket on the port side of the 2nd cylinder. The head is flat and the block is flat. I never overheated again since the first day. Any ideas why I blew a head gasket again? I am getting alot of "not sure's". I greatly appreciate any thoughts on this.

Re: 3.0 Blowing Head Gaskets

Did you torque them all down correctly? The exact procedure is in the manual, but basically start in the middle and work your way out at 1/2 torque and then do it again to the full torque value

Re: 3.0 Blowing Head Gaskets

I Agree. If you do not torque them down in the exact sequence that the manual specifies, then it will blow quickly. The mercruiser service manual says you must torque them down in this sequence or the head gasket will not last long. If you did torque them down in the right sequence then lets move on.

-what ft# did you torque the engine head bolts to?
-what type of sealer did you apply to the head bolt threads?
-did you torque them down to half the ft# then go around again torqueing them down to the full ft#?
-after you torqued them down, did you start the engine and run it to normal temps. Shut the engine off and re-torque to make sure they are at full torque?
-You said that you had the head surface "shaved" did you take it to a machine shop to shave it, or did you shave it?
-how much was shaved off the head surface?
-you said the block surface was flat. when you checked the flatness of the block surface with a straight edge, what was the biggest size feeler gauge that was able to slide between the surface and the straight edge? what was the results using the straight edge and feeler gauge on the head surface?

sorry for all the questions, but all of these can lead to a blown head gasket after a replacement.

Re: 3.0 Blowing Head Gaskets

Make sure you are using factory manual procedures and not something from Clymer or Seloc.

Re: 3.0 Blowing Head Gaskets

kszymans said:

I am looking for any ideas out there. I have a 1998 Mercruiser 3.0 181 CID. I overheated a month ago, and blew the head gasket between the 2nd and 3rd cylinders. It required a shaving of the head (the block was fine) and the replacement of four valves and the head gasket. I had to replace the water pump which was the reason for the overheat. I also rebuilt the carb, replaced the belt, the fuel lines the fuel pump and the fuel filter. I put it all back together and took it our for about four hours, never going over 50% of WOT. A week later I took it out after idling in the water for a half hour and within 5 minutes after going at 50-70% WOT, I heard a pop and took it back to the ramp. I blew the head gasket on the port side of the 2nd cylinder. The head is flat and the block is flat. I never overheated again since the first day. Any ideas why I blew a head gasket again? I am getting alot of "not sure's". I greatly appreciate any thoughts on this.

Click to expand...

Ayuh,.... Welcome Aboard,.... Which 4 valves,..??

Who determined the Block was Ok,..??

Re: 3.0 Blowing Head Gaskets

The head was done by a cylinder head shop. The block was checked by my mechanic with a straight edge and a feelr guage. The mechanic torqued the head bolts in order according to the service manual someone else in this forum sent me which was awesome. He torqued down about 50% then proceded to torque to 90. He then went to 100. We did not re-torque after that. We did adjust the rockers. After running it a bit, we did not re-torque. We put no sealant on the head bolts. With the feeler guage everything looked even. This was the second time the head was re-done, apparently. They replaced the four valves in cylinder 2 and 3. Thank you all for the questions and advice.

Re: 3.0 Blowing Head Gaskets

kszymans said:

The head was done by a cylinder head shop. The block was checked by my mechanic with a straight edge and a feelr guage. The mechanic torqued the head bolts in order according to the service manual someone else in this forum sent me which was awesome. He torqued down about 50% then proceded to torque to 90. He then went to 100. We did not re-torque after that. We did adjust the rockers. After running it a bit, we did not re-torque. We put no sealant on the head bolts. With the feeler guage everything looked even. This was the second time the head was re-done, apparently. They replaced the four valves in cylinder 2 and 3. Thank you all for the questions and advice.

Click to expand...

Ayuh,... Was the block discolored,..?? Could the area of the burn-through be Felt, with yer finger,..??

Has the motor been torn down yet,..??
Ya need the forensic evidence that it'll yield,...

Re: 3.0 Blowing Head Gaskets

Prior to removing the cylinder head, I'd take a torque wrench and check the head bolts torque as it sits right now. That will tell you if the bolts did not stay correctly tightened. Did you clean up the threads on the bolts and chase the block with a tap? Your bolts could actually be the culprit also. As sti mentioned...re-torquing after it's been heated and cooled is a must. On my recent rebuild, there was a significant torque loss after the initial heating/cooling cycle. My head rebuilder told me that as long as I start in the center of the head and work in a "circular" pattern from inner-outter bolts I'd be fine. Also, he said to tighten them down in a 3 stage process...approx 1/3 full torque each pass.

Re: 3.0 Blowing Head Gaskets

You mentioned replacing the water pump. Was it the circulation pump on the engine, or the impeller in the drive?
Did you check the cooling passages around the cylinders that had the blow-out for obstructions (thinking about localized overheating)?

Re: 3.0 Blowing Head Gaskets

the best thing you can do without a doubt is to remove the head off of the engine, and take pictures of
-the block (with the blown gasket installed)
-The head surface (showing entire head surface and valves)
-of the block gasket surface with the gasket removed.
-clean the block/head surface with some brake cleaner and paper towels and take pictures of the cleaned surfaces

By looking at these pictures, we will be able to see what is going wrong, and most likely be able point out what is making the head fail.

Re: 3.0 Blowing Head Gaskets

sti1471 said:

the best thing you can do without a doubt is to remove the head off of the engine, and take pictures of
-the block (with the blown gasket installed)
-The head surface (showing entire head surface and valves)
-of the block gasket surface with the gasket removed.
-clean the block/head surface with some brake cleaner and paper towels and take pictures of the cleaned surfaces

By looking at these pictures, we will be able to see what is going wrong, and most likely be able point out what is making the head fail.

Click to expand...

The BEST thing you can do is take it to a professional engine rebuilder and let a him examine/diagnose it. All the pictures in the world can't tell "us" what's REALLY going on. When we're talking thousanths of an inch being the difference between good to go and paper-weight...EVERYTHING other than that is only a guess.

Re: 3.0 Blowing Head Gaskets

Oshkosh1 said:

The BEST thing you can do is take it to a professional engine rebuilder and let a him examine/diagnose it. All the pictures in the world can't tell "us" what's REALLY going on. When we're talking thousanths of an inch being the difference between good to go and paper-weight...EVERYTHING other than that is only a guess.

Click to expand...

The Best thing he could do is buy a new engine, or hey maybe even buy a new boat.

I am referring to the best the OP can do if they want to proceed with trying to get help from a forum board and do the repair themselves.
There are lots of details to be seen by a picture of a blown head gasket besides the surface measurements. The color of the gasket where it blew out often tells why it broke, the condition of the rest of the gasket, the condition of the pistons, colors, so on and so on, that might not give a clear diag, but can point him in the right direction to investigate.

No one said take a picture and we will dissect it pixel by pixel and give you a sure diagnosis. it was either that or post "hmmm, call a mechanic".

Post, Brainstorm, and Evaluate, when everyone is out of ideas then call a mechanic to step in. Isn't this the whole point of a forum board?

Re: 3.0 Blowing Head Gaskets

sti1471 said:

The Best thing he could do is buy a new engine, or hey maybe even buy a new boat.

I am referring to the best the OP can do if they want to proceed with trying to get help from a forum board and do the repair themselves.
There are lots of details to be seen by a picture of a blown head gasket besides the surface measurements. The color of the gasket where it blew out often tells why it broke, the condition of the rest of the gasket, the condition of the pistons, colors, so on and so on, that might not give a clear diag, but can point him in the right direction to investigate.

No one said take a picture and we will dissect it pixel by pixel and give you a sure diagnosis. it was either that or post "hmmm, call a mechanic".

Post, Brainstorm, and Evaluate, when everyone is out of ideas then call a mechanic to step in. Isn't this the whole point of a forum board?

Click to expand...

Ayuh,..... After 3 head gaskets, the motor, Really oughta be goin' to a Machine Shop for evaluation,....

Re: 3.0 Blowing Head Gaskets

I helped re-install a head/head gasket on a yard dog (diesel truck) a few months back and the gasket blew the next day. The place that rebuilt the head sent a guy out and we stripped the head back off to find out what had happened. The bolts were all measured before we replaced the head and all were in spec and the holes were all re-tapped. When we removed the head 3 bolts were now out of spec on length so I have to ask if you have checked the bolts are in spec and the holes are clean as you could be torqueing a bolt that's bottoming out before it puts pressure on the head.

Re: 3.0 Blowing Head Gaskets

I don't know how much leeway is given concerning the depth of the head bolt holes in the block, AND I don't know if the head may have been shaved after the first head gasket was repaired, and I don't know if new bolts were ever used-- but I'm just wondering if 1 for sure and possibly 2 head shaves, combined with maybe some short bolt holes that maybe had some grit dropped in them during one or both of the prior repairs, that just maybe, the 1 or more of the head bolts is bottoming out in the block before the head is fully compressed...?

Just wonderin...

(and after I post this up I read just above me the same thing! Great minds I guess! )

Re: 3.0 Blowing Head Gaskets

sti1471 said:

I am referring to the best the OP can do if they want to proceed with trying to get help from a forum board and do the repair themselves.

Click to expand...

The definition of insanity is doing the same thing over and over again expecting different results.

While forum based repair is often very useful, there comes a point where there is no substitue for hands on professional evaluation.

I believe the OP has passed that point...one HG ago.

Re: 3.0 Blowing Head Gaskets

kszymans said:

We put no sealant on the head bolts.

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Sealant needs to be used on the head bolts, or water can work up through the bolt threads. I use Permatex Aviation sealant, dip the bolt threads and dab off a bit of the excess. The bolts need to be cleaned before reuse, wire brush the threads.

Frantically Relaxing said:

maybe had some grit dropped in them during one or both of the prior repairs, that just maybe, the 1 or more of the head bolts is bottoming out in the block before the head is fully compressed...?

Click to expand...

That and old sealant from the prior head installation. The block threads right below the bolt will have old sealant on them and if a milled head is put on the engine, the bolts will be running into the old sealant.

Pull the head and run a tap down the block holes, pay particular attention to the bottom of the holes to see if the tap digs out old sealant or rust. (Rusty threads could cause the issue too...)

Re: 3.0 Blowing Head Gaskets

kszymans said:

I am looking for any ideas out there. I have a 1998 Mercruiser 3.0 181 CID. I overheated a month ago, and blew the head gasket between the 2nd and 3rd cylinders.

Click to expand...

What is your engine serial number?

What did you set the ignition timing at?

What spark plugs did you use?

Be sure everything mentioned above is done correctly then follow the Mercruiser service bulletin link below to a T.

http://www.boatfix.com/merc/Bullet/98/98_14.pdf

Cliff notes,
Engine Models,

1997 3.0LX Sterndrive Engines: S/N 0K001529-0L000000.
1998 3.0L Sterndrive Engines: S/N 0L000001-0L097000.
NOTE:
The timing change in this bulletin is to be done only on engines listed above that
have had a blown cylinder head gasket as described in this bulletin. It does not affect any
other 3.0L or 3.0LX engines.
Situation,
MerCruiser has had several reported cases of cylinder head gasket failures that have blown
out toward the exhaust/intake manifold on the port side of the engine.
Inspection,
The most common cause of this type of head gasket failure is detonation. Usually, the head
gasket is the only part damaged. This means that the engine can be repaired by using a new
head gasket. Also, the repaired engine must have the initial ignition timing retarded to 1?
ATDC. Please follow these guidelines during the repair.
1. With the cylinder head off the engine, make sure there is no damage to the cylinder
walls, pistons, valves or cylinder head. If there is no internal engine damage, install a
new cylinder head gasket.
2. Torque cylinder head bolts to 95 lb. ft. (129 N?m) following the torquing sequence in the
engine service manual.
3. Make sure that the correct type of long reach spark plugs (AC-MR43LTS or equivalent)
is used in the engine. Be sure the spark plug gap is at .035 in. (0.9 mm).
NOTE: The use of short reach or wrong heat range spark plugs can cause detonation.
4. Be sure positive and negative battery cables are clean and tight, both on the battery and
on the engine.
NOTE: Loose or dirty battery cable connections can cause higher than normal alternator
voltage output. This higher voltage may cause the engine timing to advance more than normal.
NOTE: Follow procedures outlined in engine service manual for doing step 5 and 6.
BEFORE setting the timing be sure to do the following:
? Unplug the shift interrupter switch leads from the engine wiring harness leads.
? Plug engine wiring harness leads together.
? Install the Timing Jumper Lead.
Failure to do the above can cause an incorrect timing to be set on the engine.
Page 2 of 2 JULY 1999 98-14
5. Reset repaired engine?s initial timing to 1? ATDC.
6. Check engine idle rpm. Reset idle mixture and idle rpm back to specifications if required.
7. After the engine is running, again check the alternator?s voltage output to the battery.
If the reading exceeds 15 volts, check the charging system. Be sure that the battery
cable connections are clean and tight.
8. Apply Timing Change Decal, P/N 37-861829, in a visible location on top of the rocker
arm cover.
9. Destroy the old timing specification of 1? BTDC that is on the engine specification decal
that is on the flame arrestor or cover.
10. If the engine has a Closed Cooling Kit on it, make sure the thermostat that is in the engine
is a 140? F (60? C). Change if necessary.