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Replacing L98 heads, which is best?

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Old 11-19-2017, 07:33 AM   #21
Joe C
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GM 12378255 or 10-108 both on package. Have to crush them before adding is what I was told and easiest way is in a zip lock sandwich bag. I am thinking it was 1 tab per gallon and they come on a card of 5 as a single part. the local GM dealer had them on the shelf but forget what I paid for them though sure it was pretty cheap like 10 bucks. I used them on my Pontiac v6 the somehow looked like it got oil in the coolant and was told needed a new intake manifold as it is composite or some such crap along with all new hoses coolant flush with detergents then neutralizer and and until the bill would have come close to 1k. Had them dump coolant and rinse with hot tap water running the engine between doing it a couple of times. I added the tabs when I got the car home drove for 15 minutes and has been 2 years just fine. Same hoses manifold water pump gaskets etc. Dealer thought it was a hail mary deal and would not work but told them if coolant can't get under edge of gasket it can't corrode anything. Smart move now is change coolant every few years as corrosion inhibitors do wear out.
, that's the bottom line. I think the norm is 5 years on antifreeze coolant. you can't believe how many people never service their cooling system. they think "as long as it's green...." fairly sure it's all about the acidic level of the solution. i'm no chemist, but I guess once it drops below the pH 7 level, it starts eating away at the metal parts of your engine and cooling system. . three areas where I probably "over-service" my corvette is the cooling system, (automatic) transmission, and differential. brake fluid is a close second. most of the time, it's because I have nothing better to do. i'm alone, in my garage, spending quality time with baby. its therapeutic -

BTW, and FWIW -- as previously stated, I add three delco cooling tablets to my cooling system after doing a valve job. nowhere on the package directions state to crush the tablets prior to use. I basically popped the radiator cap, and dropped in the tablets. crushing the tablets would not hurt anything though, and I guess it would aid in dissolving the tablets and dispersing the product, but it's not a "have to" thing.
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Old 11-19-2017, 11:58 AM   #22
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Service manager told me to crush them so they go to work much sooner.
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Old 11-19-2017, 08:09 PM   #23
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Service manager told me to crush them so they go to work much sooner.
Yes these sealing tabs will plug fine voids & pinhole leaks and should be crushed into a fine powder to facilitate circulation throughout your cooling system.
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Old 11-21-2017, 01:37 AM   #24
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polo. might want to look into hylomar.

as a gasket coat.
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Old 12-05-2017, 09:03 PM   #25
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I want to update you all on my head situation. The advice saved me a bundle and the 91 runs perfect and no coolant loss issues. I did use my old heads with MLS head gaskets (.041" thick and 4.065" bore.) The heads have now been resurfaced twice now, I don't know if the compression has changed much, but runs fine on 93 octane. Thanks again guys, there is some real good info to be had on this forum.
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Old 12-06-2017, 02:38 AM   #26
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I want to update you all on my head situation. The advice saved me a bundle and the 91 runs perfect and no coolant loss issues. I did use my old heads with MLS head gaskets (.041" thick and 4.065" bore.) The heads have now been resurfaced twice now, I don't know if the compression has changed much, but runs fine on 93 octane. Thanks again guys, there is some real good info to be had on this forum.
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Old 12-06-2017, 07:22 AM   #27
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I am swirching to AFR 195 heads
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Old 12-06-2017, 09:34 AM   #28
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Quote:
Originally Posted by polo91 View Post
I want to update you all on my head situation. The advice saved me a bundle and the 91 runs perfect and no coolant loss issues. I did use my old heads with MLS head gaskets (.041" thick and 4.065" bore.) The heads have now been resurfaced twice now, I don't know if the compression has changed much, but runs fine on 93 octane. Thanks again guys, there is some real good info to be had on this forum.
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Old 12-06-2017, 07:14 PM   #29
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I want to update you all on my head situation. The advice saved me a bundle and the 91 runs perfect and no coolant loss issues. I did use my old heads with MLS head gaskets (.041" thick and 4.065" bore.) The heads have now been resurfaced twice now, I don't know if the compression has changed much, but runs fine on 93 octane. Thanks again guys, there is some real good info to be had on this forum.

VERY GLAD to hear that !!!!!!!

Always nice to get a happy ending !!!
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Old 12-06-2017, 10:14 PM   #30
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Quote:
Originally Posted by polo91 View Post
I want to update you all on my head situation. The advice saved me a bundle and the 91 runs perfect and no coolant loss issues. I did use my old heads with MLS head gaskets (.041" thick and 4.065" bore.) The heads have now been resurfaced twice now, I don't know if the compression has changed much, but runs fine on 93 octane. Thanks again guys, there is some real good info to be had on this forum.
Good news to hear.. But what did you use for the fix this time? Sealant tabs? Sealant coated gaskets? Feedback helps us all.
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Old 12-07-2017, 11:49 AM   #31
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Good news to hear.. But what did you use for the fix this time? Sealant tabs? Sealant coated gaskets? Feedback helps us all.
My fix was MLS head gaskets off of Ebay from CGM Motorsports ($90) and ARP bolts ($75). In the past when I have rebuilt Chevy engines not much attention was paid to head gaskets. I discovered the hard way that the GM head aluminum castings have very little tolerance for generic head gaskets. What I'm trying to say is that the bore size on the gasket needs to be as close to the bore size of the block as possible. No sealants were used, just correct size gaskets.
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Old 12-07-2017, 12:58 PM   #32
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Default thnx for sharing solution

so you did not get the aluminum heads decked at all?
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Old 12-07-2017, 03:07 PM   #33
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so you did not get the aluminum heads decked at all?
The heads were resurfaced, I guess that is the same as decking.
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