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Need head gasket job advice

 
Old 11-17-2018, 01:14 AM
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woodcrest
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Default Need head gasket job advice

OK, my 89 C4 350 needs a head gasket job. I have spoken with a parts guy (owner of a C4) and he said because of the tight quarters it is easier to unbolt the whole front assembly of the car (4 bolts) and slide the assembly out from the body under a raised car. Is this the way to go? I have looked on youtube about this, but have been unsuccessful. Because of the iron block and aluminum heads, I have been told it is common for head gaskets to fail on the Corvette, true? Best to install metal gaskets and overtorque by 7 lbs or so? What if compression tests indicate the left side (non air conditioner side) is the problem, but the right side shows strong compression, tempting to just do gasket on the left side. Very thankful for any advice.
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Old 11-17-2018, 06:14 AM
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Joe C
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Originally Posted by woodcrest View Post
OK, my 89 C4 350 needs a head gasket job. I have spoken with a parts guy (owner of a C4) and he said because of the tight quarters it is easier to unbolt the whole front assembly of the car (4 bolts) and slide the assembly out from the body under a raised car. Is this the way to go? I have looked on youtube about this, but have been unsuccessful. Because of the iron block and aluminum heads, I have been told it is common for head gaskets to fail on the Corvette, true? Best to install metal gaskets and overtorque by 7 lbs or so? What if compression tests indicate the left side (non air conditioner side) is the problem, but the right side shows strong compression, tempting to just do gasket on the left side. Very thankful for any advice.
(no flames - just trying to understand your post) -- am I reading this right - unbolt what and raise what? , it's tight, but to R&R head gaskets, top side and in car, works just fine. just get everything out of the way. it may be easier with a dropped engine (if i'm reading you right), but it seems like a whole lot of extra, unnecessary work. newsflash - besides being a really dumb idea, there's more than 4 bolts involved. did I say dumb idea? well it's a stupid idea, and obviously someone hasn't thought this through. just the logistics of this would be beyond, even the best, most well equipped shops. it is somewhat common for head gaskets to fail on aluminum head L98's - usually, either #7 or #8 cylinder. some, including myself, think that it has something to do with the restricted coolant flow of the manifold gaskets. some folks replacing manifold gaskets opt for open rear coolant port gaskets (85 iron block style). I did this on my 90 corvette and did not experience any temperature related cooling issues. if you have to do one side, might as well do both. shortcuts have a way of coming back to bite you in the ****. if you have to run one head through a machine shop for the warpage/flatness thing and variations in gaskets between new and old, could cause you issues. personally, I would do both. gaskets - you can't go wrong with fel-pro. not sure what's the latest and greatest for the aluminum head small blocks. never heard of this overtorque by 7 lbs thing. was this more advice from your parts guy? just askin'. can't go wrong with factory torque specs with stock applications. as you can see from the attached pic, plenty of room - it's not all that tight. unbolt, remove, and pull back everything and anything in the way. (my 2-cents)





Last edited by Joe C; 11-19-2018 at 01:28 PM.
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Old 11-17-2018, 08:36 AM
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I would do both, you are most of the way there. I would also go with a Felpro gasket set unless you plan on modifying the engine.

Gary
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Old 11-17-2018, 09:04 AM
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You can take advice about parts from a technician, but don't take technical advice from the parts counter.
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Old 11-17-2018, 10:35 PM
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I blew head gasket on my 89 last year. Driver side, number 7. Corvette shop wanted way to much to do it, so I did it myself. Used a field service manual and had no problems. Did not have to pull engine and did
both sides. Also had both heads milled flat so maybe I won’t have to do it again. I had a lot of choices on head gasket , but I decided to go with what Chevy recommended which was a .051 thickness. Compression calculation program shows I have compression just under 10 to 1 which is
perfect for me. Good luck
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Old 11-17-2018, 10:47 PM
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Do them both.. Once you're down that far it is nothing to get the second gasket while you're there.

Agree with everyone above - Do it in the car. It's not a bad job. I did heads, cam and even bearings, rings and an oil pump without pulling the engine. It's not as scary as it looks.

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Old 11-18-2018, 07:42 AM
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Originally Posted by woodcrest View Post
OK, my 89 C4 350 needs a head gasket job. I have spoken with a parts guy (owner of a C4) and he said because of the tight quarters it is easier to unbolt the whole front assembly of the car (4 bolts) and slide the assembly out from the body under a raised car. Is this the way to go? I have looked on youtube about this, but have been unsuccessful. Because of the iron block and aluminum heads, I have been told it is common for head gaskets to fail on the Corvette, true? Best to install metal gaskets and overtorque by 7 lbs or so? What if compression tests indicate the left side (non air conditioner side) is the problem, but the right side shows strong compression, tempting to just do gasket on the left side. Very thankful for any advice.
"FOUR BOLTS"??

VEDDY INTORESTINK!




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Old 11-18-2018, 12:11 PM
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Originally Posted by woodcrest View Post
What if compression tests indicate the left side (non air conditioner side) is the problem, but the right side shows strong compression, tempting to just do gasket on the left side. Very thankful for any advice.
Not a good idea IMHO. Do the job right.
While you're in there exerciser good judgement and replace those items with life limits. Water pump, belt tensioner and pulley. Maybe even the crank pulley if yours is showing signs of delamination. So many components are now accessible, why not get the job done once?

Good Luck

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Old 11-19-2018, 02:45 AM
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Originally Posted by woodcrest View Post
I have spoken with a parts guy (owner of a C4) and he said because of the tight quarters it is easier to unbolt the whole front assembly of the car (4 bolts) and slide the assembly out from the body under a raised car. Is this the way to go?.
Terrible idea! They did load the chassis and running gear into the body from the bottom at the factory, but that's no way to replace a head gasket! I've had my heads off twice, and it's not that hard, just a lot of details.

You do have the FSM, don't you? Take pictures of your progress, keep bolts separated for each step of the disassembly, and mark your wires. After you remove the exhaust manifolds, stuff a rag into each exhaust pipe to keep from dropping a bolt or tool down the pipe. To minimize coolant getting into your cylinders, siphon coolant out of the engine by removing one bottom bolt from each head, then slide a small hose into the bolt hole, put your finger over the end of the tube and pull the tube out of the hole. Lower the end of the tube and coolant should flow from the tube. Do both sides.


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Old 11-19-2018, 11:49 AM
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Originally Posted by confab View Post
Do them both.. Once you're down that far it is nothing to get the second gasket while you're there.

Agree with everyone above - Do it in the car. It's not a bad job. I did heads, cam and even bearings, rings and an oil pump without pulling the engine. It's not as scary as it looks.

with CONFAB and others. I've done everything mentioned except replacing the cam on a C4. But, by pulling the radiator etc.(and bumper??) and that is possible too!

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Old 11-19-2018, 12:55 PM
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Originally Posted by Paul Workman View Post
with CONFAB and others. I've done everything mentioned except replacing the cam on a C4. But, by pulling the radiator etc.(and bumper??) and that is possible too!
radiator, yes; bumper, no
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Old 11-19-2018, 11:36 PM
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By FSM, do you mean the Shop Service Repair Manual? Field Service Manual?
Curious why your heads have been off twice, both blown gaskets? If so, how much time/mileage between each?
Thanks for the excellent input
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Old 11-19-2018, 11:38 PM
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Thanks all for the excellent input, more and more thinking I can do this, thanks to all your input!
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Old 11-20-2018, 01:52 AM
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Originally Posted by woodcrest View Post
By FSM, do you mean the Shop Service Repair Manual? Field Service Manual?
Curious why your heads have been off twice, both blown gaskets?
I'm guessing you're talking to me.
FSM . . . Factory Shop/Service Manual, by Helms Inc. Detroit MI (Not Haynes or Chilton's)
First . . . Complete rebuild @ 185,000 miles. (Note the unusual pistons, as opposed to Joe C's in post #2.)
Second . . . Cracked heads, casting #...624 (notorious for that).

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Old 11-20-2018, 02:01 AM
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That would be the shop manual as printed by GM?
Should check if my casting is .....624? If they are...new heads from Summit?
I do not see what is unusual about the pistons....please fill me in,
Thanks
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Old 11-20-2018, 03:14 AM
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SBC iron heads info:

Notice the valve reliefs. Joe has the original pistons, which must be installed with the valve reliefs toward the intake manifold. This means the wrist pin must be in the center of the piston, so the pistons on one side of the engine are upside down from the other side of the engine in relation to the rotation of the engine. (The "front" of the piston on one side is facing the "back" of the engine on the other side.)

My pistons have a notch that faces the front of the engine, because my pistons have the wrist pins slightly off-center in the piston. This requires four valve reliefs, because the pistons must all be oriented facing the same direction. This "off-center" of the wrist pin reduces the side loading of the piston during the power stroke to reduce piston skirt wear and slightly increases the power output of the engine because of the reduced friction. There is a slight change in the con rod angle, too.

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Old 11-20-2018, 10:40 AM
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If you can't find a FSM? A subscription to alldatadiy is cheap and a really good alternative.

I paid 26 bucks for a year, I think?

For a lot of jobs I like it better.. Like wiring for example. You can print out a diagram, drag it all over the car, write on it, get it filthy.. then just throw it away and print a new one next time.

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Old 11-20-2018, 11:34 AM
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Originally Posted by woodcrest View Post
That would be the shop manual as printed by GM?
Should check if my casting is .....624? If they are...new heads from Summit?
I do not see what is unusual about the pistons....please fill me in,
Thanks
Where would I find the casting number? Can I read it before I pull the heads?
Thanks again.
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Old 11-20-2018, 04:21 PM
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Originally Posted by woodcrest View Post
Where would I find the casting number? Can I read it before I pull the heads?
Thanks again.
we seemed to have gotten side tracked with the OP checking for IRON head "624" castings. original post stated he has a 1989, aluminum head L98, and if original, would be casting no. 10088113.
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Old 11-20-2018, 04:42 PM
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Originally Posted by Joe C View Post
we seemed to have gotten side tracked with the OP checking for IRON head "624" castings. original post stated he has a 1989, aluminum head L98, and if original, would be casting no. 10088113.
Sorry. Side track on iron heads was not intentional. Differences in pistons is still relevant, though.

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