'96 Pro Star blew a head gasket

[2Valve]

We verified last evening that my buddy's boat has a blown head gasket (350 Chevy block).

 

It's on the starboard side.

 

Was wondering if we can just use automotive gaskets and if it's necessary to purchase new head bolts. If anyone can point me to the torque spec's for the head, exhaust and intake manifolds, I would appreciate it.

 

Thanks,

 

2Valve

[2Valve]

I forgot to add it's a '96 MC, non LT-1 engine. 275hp I think.

[MDB1056]

It happens. My 92 Hydrodyne Comp has GM 350 Mercruiser marinization (Magnum). Same issue a few years back at ony 550 hrs. No way to know if orig gasket had a defect or what. Automotive gaskets are fine. I used Victor Reinz gaskets - very good quality. No issues since. Head bolts shoudl be fine. Don't recall torque specs but any machine shop should be able to tell you. Keep skiing

[thager]

Check the exhaust manifold riser gasket first. I had water in my oil and was sure it was head gasket when actually exhaust manifold riser gasket. 74 Hydrodyne.

[2Valve]

@MDB1056 Thank you sir! He had a previous problem with the motor going into limp mode because it would overheat. Come to find out, it had two thermostat's installed and one was failing. Apparently, you can install a t'stat in the hose riser assy. above the water pump as well as the traditional location in the front of the intake manifold. I'm thinking, that maybe the engine overheated and possibly warped the starboard head. Something we'll definitely check upon removal.

 

[2Valve]

@thager good point. We checked the oil Sun night and it appears clean with no evidence of water. thanks, 2Valve

[BrennanKMN]

Get new head bolts. They are quite often torque to yield (TTY) bolts meaning they are toast after you've used them once. People do re-use them, but am a torque freak.

[BraceMaker]

@BrennanKMN i am as well which is why I always install studs and then those are reusable.

 

 

[Jetsetr]

Go with a permatorque head gasket as well...only need to torque it once...

Better make sure the head isn’t warped if it overheated...easy to take a few thousands off to true it up (machine shop).

[Orlando76]

New bolts. Don’t forget to check direction of Eder gasket as one side goes forward and the other opposite. That is if Indmar is same as PCM.

[MDB1056]

Always good advice to have a shop check the head for warp or crack. When my gasket failed- water got in and hydrolocked. I lost one head. Other was fine. I had entire engine rebuilt - and one new head - I reassembled and installed - that was 250 hours ago. New head bolts are cheap insurance if you’re inclined. Always torque to specs and check check check. Victor Reinz gaskets are excellent quality

[DW]

FYI - Marine head gaskets have stainless steel combustion rings, automotive gaskets do not. So if raw water cooled, marine head gaskets are what you want to go with. Automotive ones work, but won't have the corrosion protection.

 

@2Valve - have you verified why the gasket failed, most likely between cylinders 3/5 since the exhaust valves are siamesed and adjacent there. Do a good inspection to the cooling passages to ensure not blocked and limiting coolant flow in the hot zone. Also, make sure you get one that is the same thickness, you can get various thickness options for the SBC.

[2Valve]

@DW

We haven't pulled the head. Hope to do that later today. Low compression was seen between cylinders 4 and 6.

 

We'll be checking for warpage on the head and block in that area as well as the cooling passages. The motor over-heated about a month ago but was running fine until last week.

 

Thanks for the head's up on the marine grade SS gasket material. The engine is RWC.

 

[MDB1056]

Victor Reinz is owned by DANA corp. Go to danaaftermarket.com and Victor Reinz has en entire menu of marine applications including Holman Moody, Indmar, Mercruser, Chevrolet Marine, GMC Marine, Ford Marine, and many more. Reinz gaskets are very high quality.

[DW]

@2Valve - it can take a while after an overheat to cycle the head gasket to failure, and right between the siamesed exhaust ports, 3/5 & 4/6.

[2Valve]

@MDB1056 Thanks for the info. One of our members is an Engineer at Dana, so I'll pass this along.

 

[2Valve]

@DW So the head gasket is definitely open between 4&6. We measured the head and block and thankfully, there is zero warping. We decided to pull the port side head too and will have both cleaned up before re-installing with marine grade gaskets. There's quite a bit of rust, crud, in the water channels so we figured, clean them up while we have it apart.

[Jetsetr]

That’s a good move pulling the other head...all the work is done and it’s just a few more bolts...

Your engine will like that...

PLUS if it got hot there might be damage on the other side as well...might save you a bunch of work to change the other gasket when you could be skiing.

[2Valve]

Heads should come back tomorrow from the shop.

 

Funny, I tried but couldn't talk my buddy into getting them ported and polished.

 

A Roots Supercharger would have been cool too :)

 

[DW]

@2Valve - for an inexpensive 'wake it up' option, a ZZ4 camshaft is a pretty nice match for great idle and improved air flow at higher RPM. It has more lift over the marine cam and does not hurt idle quality.

[2Valve]

@DW Thanks for the tip. I love a motor with a silky smooth idle. One of the great sounds is the LS1 in my Vette.

[MDB1056]

Agree 100% with @Jetsetr - it's a given that with headgaskets you always do both if one has been damaged. Always.

[2Valve]

Update on my buddy's boat. Only issue was a blown gasket between 4, 6 cylinders. Checked everything for warpage, and had the heads cleaned up and milled .002". Valves, valve seats, seals and springs were deemed "excellent", so we left those alone. The motor's never burned oil either.

 

Got it all put together last night. Took our time setting valve lash/pre-load on the lifters, which I haven't done since I was a kid on a 327 Impala. I'm used to solid lifters, valve clearances on old motorcycles, so had to re-train my brain how the hydraulic lifters actually work. :)

 

Popped the distributor in and it fired right up. Silky smooth idle, and quiet as a mouse. Set the timing and took it out for a spin. Literally sounds and runs like a brand new motor. Couldn't ski since the lake had whitecaps, but we'll run it through our course tomorrow.

2Valve

[skihacker]

It's always a deep sigh when you hit the key and it just...........starts. No popping or noises or looonnnng crank.

[2Valve]

@skihacker Exactly. Confirms that you did it all perfect. The most fun was assuming the squat position to set the torque on the 34 head bolts in three stages. :( My legs felt worse than running 8 sets in the course.

[2Valve]

One more question for y'all. We got the timing close (as we marked the distributor position on the intake manifold), but idle is a tad high. Under the assumption that the timing is advanced, is the timing mark on the cover marking TDC? (see photo). I'm going to pick up some harmonic balancer timing mark tape today. And I have the CodeMate tool to put the system into base mode, but wasn't 100% sure that the timing mark on the timing cover indicates TDC or the 10 degrees advanced, when setting the timing, as aligned with the slit on the harmonic balancer.

 

btw, my buddy nearly broke his ankle this past Sat morning. Wanted to use his boat in the course, since we got it running. He's first up. Weather conditions horrible, (but we could care less), and he goes out the front around 1. Right now, it's a severe sprain, so just hoping to help him get this completed.

 

[DW]

Not sure on how your particular timing cover is marked, but if only on notch it just might be the base timing mark. You might look at the flywheel, there is usually a removable plug on the top of the bellhousing and the flywheel may be marked at TDC. Next option would be to grab a TDC stop, pull #1 plug and verify TDC 'the right way' :-)

[2Valve]

@DW thanks for the advice. We were in such a rush to get it running that we never bothered to determine if that mark was true TDC or the base timing mark (10 degrees BTDC). I'll look for the bellhousing plug tonight, but I'm thinking it's just easier to pull the plugs and get #1 on TDC, as you suggest.

Thanks,

2Valve

[DW]

@2Valve - since you are marking the damper with a timing tape, you may as well document full advance, which is the more important parameter. Should be 32-33 deg BTDC for a GM small block.

[2Valve]

@DW, good point. I'm guessing that full advance occurs around 3k rpm?

Thanks, 2Valve

[DW]

@2Valve - it all depends on the timing curve and 3k is a good estimate.

[BraceMaker]

96 prostar has mefi so you need to make a tool to put it in timing mode and then it's timed to -10

 

I would caution against trying to time to TOTAL advance - because MEFI uses the RPM as well as values from the MAP sensor so total advance can be between say 28 and 35 degrees depending on the input from the MAP.

 

Basically its hard to know what advance the MEFI is asking for unless you have some way to read the sensor values and access to the background tune so that you could check that for at 4000 rpm the tune is asking for X amount of advance when there are 46 KPA of manifold pressure etc.

 

Instead you want to place it in timing mode and then set base timing - or go with your mark and try a tiny fracture more/less rotation on the distributor until the running attributes are as you desire.

[BraceMaker]

https://www.rinda.com/acro/codemate.pdf

 

You can buy the tool from michigan motorz, ski dim, rinda etc.

 

Or you can use an LED and a paper clip stuffed in the port -

 

Or I personally made one using one of these https://www.ebay.com/itm/10-Way-Aptiv-Delphi-Metri-Pack-150-Series-Connector-Pigtail-12045808-6-inch-Wire-/283516169356?hash=item4202e16c8c along with an LED and a switch.

 

 

[2Valve]

@BraceMaker I have the CodeMate. It's not 100% clear about the base timing instructions but I believe the Code mate is installed, engine off. Start motor and turn the Code Mate on, which would put the engine in base timing mode?

Then set to -10 degrees BTDC.

Thanks,

2Valve

[chrislandy]

just bridge A&B on the connector with a paperclip and start the engine (or you can do it when the engine is running), then set to 10deg BTDC, the timing mark is usually TDC.

[BraceMaker]

As Chris pointed out - bridging the A&B on the DLC will set service/timing mode - but if you're going to do this please put some sort of fuse in it.

 

A Code mate is literally just a 10 way Metri-Pack 150 series connector with an LED that bridges F/E and a Switch with a fuse that Bridges A/B.

 

If you stuff an LED into F/E on the connector it should light up when you turn the key on and turn off when you start the boat - if that LED blinks or stays on when running you have a fault stored. You then turn off your ignition and stuff a paperclip across A/B and turn the key to the on position it will start blinking out your trouble codes. If you start it with it bridged you're in timing mode.

[2Valve]

@BraceMaker

Got it. So I'll install the CodeMate with engine off, switch it to On and then start the motor and time away. :)

Thanks very much. I'm a points and condenser, dwell meter kind of a guy, so this new fangled electronics stuff is very new school.

Appreciate it. Still another month of skiing left up here in the North.