Blown HG: What am I up against?

[FlyingDutchman]

Car must have overheard my conversation about buying a more fuel efficient daily driver

Some background on the car: '97 Z28, just rolled 118k, actually blew a HG in 2008 but ended up bending a rod. So, motor was rebuilt with fresh seals at around 64k by a local mechanic. Nothing crazy done to the car, just whatever is listed below. It's seen maybe 30 track passes in its life, as recent as 2 weeks ago.

Fast forward to today. Car has been running great with no problems.. until I was on my way home and at a stop light it started misfiring. Using Dash Command on my phone, it indicated Cylinder #7 to be misfiring. I figured it might be something dumb like a loose spark plug (has OTVC setup, so wires are good) or something of the likes.

Idling in the driveway and I notice an awful smell and a bit of smoke, but its cold so I just assume its normal for this time of year. Shut the car off for a bit to do some reading and return a short while later only to find nothing obviously wrong. I then thought maybe the opti was taking a dump or having issues with the heavy fog this morning.

So I start it up again and it idles like ****. I notice a pillar of white smoke behind me and shut the car off. Talk to my dad a bit and go to show him whats going on. Attempted to turn the car over only to be greeted with an all to familar BANG! but not as loud as the one in 2008 (oddly enough, I parked in the same spot in the driveway where this same thing happened...) Obviously the motor is now hydro-locked

To verify my assumption, I check the radiator (empty) and pop the oil fill cap off (looks like phlegm). Unless I'm overlooking things here, I think its the passenger side HG which may also be the same side this happened to 54k miles ago.

So my options are:
1) Burn the car to the ground and move on with life
2) Bring it to a mechanic and probably pay around $1500+
3) DIY

Tempted to do it myself I've pulled the intake off, did the exhaust, upgraded brakes, etc. so I consider myself mechanically inclined, but this would be a whole new level.

I've read quite a few threads and stuff about the basic removal and what not. But a few questions remaining I haven't found solid answers for yet include:
1) Can this be done on the car without dropping/pulling the motor?
2) How do you clean all that nasty sludge/phlegm-like stuff out?
3) How can I be 100% its the HG and not like a random hole in the water jacket? (ruling out all possibilities)

I'm sure I'll come up with other questions...

Sorry for the long post

[LTb1ow]

Start by doing a pressure test of cooling system, and then verify that a HG is leaking.

If it is, personally I would do both HG but thats me. Its doable without taking the motor out, but since you don't strip it down to hot tank the block you will never have it completely clean. You can try to fix it, and cycle oil out of the engine frequently till you are confident its cleaned up. If you caught it soon enough and don't have a bent rod I would say just R&R HG is fine.

When you do pull the heads, check each piston at TDC to make sure you didn't shorten anything. I would recommend ARP head bolts and a quality HG set. Get everything as clean as possible and have your heads checked for straightness. Toss a straight edge on the block as well. Stock head bolts call for TTY so you will need an angle torque wrench, or use ARP which use a straight torque spec.

If you can follow bolt torque sequences and can work in odd angles its most def doable.

[NastyEllEssWon]

well if you go for option 3, to fix it and its too far gone to fix, then option 1 seems like a good option at that point and you've saved yourself 1500 bucks.

[NJSPEEDER]

Head gaskets are more messy and time consuming than they are difficult. I would go with option 3.

[redsoxsstink]

they make engine cleaners. you run your 4.5-5qts of oil pour this stuff in, let engine get to operating temp and it cleans out the engine for cases like this. or your can run a quart of ATF instead of a quart of oil with the same procedure. naturally you dont want to run this stuff any longer than needed so drain and new oil and filter goes in right after you are done. i also changed my oil after 100mi after the flush

i did this with my brand new motor when the intake gasket blew to improper mating of the aftermarket intake to the new heads. LT!Blow, basically summed it up. obv working on a 4thgen is never comfortable but it is a pretty strait forward job.

[BonzoHansen]

Originally Posted by redsoxsstink

they make engine cleaners. you run your 4.5-5qts of oil pour this stuff in, let engine get to operating temp and it cleans out the engine for cases like this. or your can run a quart of ATF instead of a quart of oil with the same procedure. naturally you dont want to run this stuff any longer than needed so drain and new oil and filter goes in right after you are done. i also changed my oil after 100mi after the flush

i did this with my brand new motor when the intake gasket blew to improper mating of the aftermarket intake to the new heads. LT!Blow, basically summed it up. obv working on a 4thgen is never comfortable but it is a pretty strait forward job.

that flush crap opens up every leak in site and dislodges every piece of dirt inside that engine. if the bearings are not already shot a flush job will finish them.

drain the pan, change the filter. get it running up the temp, stop, change oil & filter again. Do it a few times. Use cheap oil if you want to save a bit.

[ThoR294]

Originally Posted by BonzoHansen

that flush crap opens up every leak in site and dislodges every piece of dirt inside that engine. if the bearings are not already shot a flush job will finish them.

drain the pan, change the filter. get it running up the temp, stop, change oil & filter again. Do it a few times. Use cheap oil if you want to save a bit.

+1 to this

[redsoxsstink]

the motor was gone through fairly recently, with freq oil changes it should be pretty clean. just stating what i have done. or if that flush stuff doesnt make you feel warm and fuzzy inside, you could use diesel too.

[NJSPEEDER]

Oil is plenty to rinse through the engine. No need to thin it with diesel or additives.

The diesel trick isn't uncommon for heavy equipment and commercial diesels that run very thick oil and lots of it so it dilutes quickly. On a gas engine that only holds 5 quarts and runs such light weight the same trick would add a particulate scrub while further thinning the oil. This is a dangerous combination for an engine with some miles on it.

[sweetbmxrider]

You blew a head gasket on a motor that had previously blown a head gasket. You think its the same head gasket that went bad. You previously hydro-locked the motor and bent a rod. You believe you hydro-locked it again. You want to replace the blown head gasket only?

[ThoR294]

I would check the heads/block to make sure they are straight before doing the head gaskets...

[sweetbmxrider]

The block won't be straight, the deck height is off from the factory. I would certainly look into getting both heads shaved down to straighten them and without a doubt use ARP hardware.

[BonzoHansen]

Originally Posted by sweetbmxrider

You blew a head gasket on a motor that had previously blown a head gasket. You think its the same head gasket that went bad. You previously hydro-locked the motor and bent a rod. You believe you hydro-locked it again. You want to replace the blown head gasket only?

ouch, didn't know that. If it really locked this time I'd pull the motor.

[sweetbmxrider]

Originally Posted by BonzoHansen

ouch, didn't know that. If it really locked this time I'd pull the motor.

If I read his post correctly, yes.

[greenformula92]

I read it that way too Adam. If it hydrolocked again you might as well pull it and at least go through everything

[FlyingDutchman]

Originally Posted by sweetbmxrider

The block won't be straight, the deck height is off from the factory. I would certainly look into getting both heads shaved down to straighten them and without a doubt use ARP hardware.

Originally Posted by sweetbmxrider

You blew a head gasket on a motor that had previously blown a head gasket. You think its the same head gasket that went bad. You previously hydro-locked the motor and bent a rod. You believe you hydro-locked it again. You want to replace the blown head gasket only?

Originally Posted by greenformula92

I read it that way too Adam. If it hydrolocked again you might as well pull it and at least go through everything

Above is the piston that came out. As you can see, the connecting rod is not very straight..

I think it was the same side as the misfire was detected on. Tmr I will pull the spark plug out and see if anything comes out of Cylinder #7. Last night I was in a bit of a panic as it is my DD and I don't currently have a spare, so I was thinking of a quick fix for now. However, transportation for the short term has been taken care of and I am on the hunt for a lease. It's too cold to play with the car now. I also want to do some more research before I tear the car apart.

I have been tossing the idea around of doing a h/c package for a while now, guess this is a sign I should get on that lol my thoughts are shipping out the heads for the LE2 package (they have to be checked anyway, right? plus then the top end would be fresh) with a mild/street-able cam, something that'll push the car into the 12s. While the heads are away, I'd probably have the block checked and cleaned, although I am not sure how much that would be, maybe someone has a ballpark number? Figure new cam/main bearings (even though the current motor makes a good 22 psi hot idle and 42 psi at highway speed, based on dash gauge reading, not a mechanical gauge) unless that's overkill.

Weird thing about this whole situation is that the car went for 54k miles and just gave out, no indication this was coming lol

[sweetbmxrider]

I'd go 355 on the bottom end with the stock crank polished up if it checks out. Decent rods and pistons, bump the compression up a little, do the top end like you are thinking, have a fun motor when you are done. Probably around $4k all said and done. Pick your end goal now and stick with it. Figure out what you want out of it, what you want it to do and when, and how much you can budget to it. There's several people here and on ls1lt1 that can give you great direction.

[LTb1ow]

Establish budget and then its easy.

[greenformula92]

Originally Posted by LTb1ow

Establish budget and then its easy.

the hard part is sticking to said budget

[NastyEllEssWon]

Originally Posted by greenformula92

the hard part is sticking to said budget

this is why you do your shopping after the budgets established. putting together a parts list is the easiest way to snowball a project. set a number and do some heavy searching on the internet to find out whats the best products you can purchase that will get you at the end goal of being repaired lol I remember putting together lists of STUFF i want then looking at the number and being like

edit for censor

[Pampered-Z]

118K - if the rest of the car is in good shape and you want to keep it I'd pull it, build a new motor.

you could waste time and money fixing the gasket only to find you have more issues like bearings etc. Very odd to be blowing head gaskets.

[greenformula92]

Originally Posted by Pampered-Z

Very odd to be blowing head gaskets.

I wouldn't call it odd. I have seen ALOT of LT1 motors with blown head gaskets. Odd after a rebuild....maybe. But not odd in general

[FlyingDutchman]

With help from Jersey Mike and Chase (The3lite) we were able to pull the motor out this weekend with minimal breakage, actually went pretty smooth! Looks like a cracked head gasket at the end of the block by Cylinder #7 again. Crack is right in line with the coolant passages/bolt holes. Gaskets came off pretty clean. Will post pictures tonight.

[FlyingDutchman]

As promised, pictures. You may have a problem if coolant pours freely from your exhaust



Cylinder #7 - Note the gasket shape near the 5 o' clock position. The gasket was also partially in the bore around the 4 o' clock position Not sure on the gasket brand, but it seems pretty thick! Was same side as last time based on the cleanliness of the piston vs the rest of them


Block side of the gasket, you can see the deterioration/crack in line with the coolant passage/bolt holes.


Tried to get a close up shot of the head side of the gasket. Looks like a valve made a slight imprint on it. It also looks like the Dexcool was eating the gasket. Will be going green next time around.

[sweetbmxrider]

Nice carnage