Cracked Cylinder Head 92 SNOB
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=31923
Printed Date: October-08-2024 at 5:24pm
Topic: Cracked Cylinder Head 92 SNOB
Posted By: ibiz
Subject: Cracked Cylinder Head 92 SNOB
Date Posted: October-31-2013 at 10:07pm
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So it looks like I have a cracked cylinder head on my 1992 Nautique Open Bow with the 351 ford and 750 hours. Water is leaking (sprouting out at WOT) into the bilge. There is no water getting into the cylinder, oil, etc. The engine runs great from idle to WOT. It probably has been like this all season and maybe last year also. Not sure how it happened. The boat is winterized and stored in facility that stays 60 degrees all winter. Some suggestions I have received are: 1. The boat runs fine, run it until it dies. 2. Replace the one head. 3. You must replace both heads at the same time to get good results. 4. Replace the whole block because after you replace the heads you will find out that you needs rings and piston work and by that time you might as well invest in the new engine given that yours is 23 years old and has 750 hours on it. Anybody have experience with the same or similar issue? Thanks. |
Replies:
Posted By: Gary S
Date Posted: October-31-2013 at 10:21pm
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First off 750 hours are not alot. Do you know what heads are on there now? E7's or GT40? I seem to remember that GT40's were prone to cracking. Some here have used jbweld, since it was an outside leak, with suscess. You could try that and in the mean time find yourself a set of GT40P's,97 & up 5.0 Explorers and Mountaineers, and have them ready to go when you need them ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: gun-driver
Date Posted: October-31-2013 at 11:09pm
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Happened to my '95 GT 40 EFI. Drill very small holes at ends of crack, Vee out crack, JB Weld. Had to reapply/add more JB Weld every year. But it lasted about 3 years for me but eventually you're going to have to replace it. Best bet would be to replace both with a set of 40 P's as regular 40's are getting hard to find plus you get a bump in performance from the P's |
Posted By: ibiz
Date Posted: October-31-2013 at 11:41pm
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Thanks for the idea. How can I tell if they are E7s or GT40s? Don't mean to sound too stupid but and you drill the ends and jb weld while it is still on the block or do I have to take it off? What was the size of the crack you filled with the jb weld? |
Posted By: Gary S
Date Posted: November-01-2013 at 12:29am
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http://www.fiveohinfo.com/performance/gt40-gt40p.html#identify" rel="nofollow - Here is a link that might help identify yours. You can post some pictures and maybe someone can tell too. Paul you say GT40 heads are getting hard to find,would I be correct in assuming that all GT40s can have the same cracking issues? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: ibiz
Date Posted: November-01-2013 at 12:40am
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Are the GT40 and GT40P heads interchangeable? Or will I need to do something to get the 40P to fit if the current head is a GT40? And it is essential to replace both heads at the same time? |
Posted By: Gary S
Date Posted: November-01-2013 at 1:16am
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Yes for marine use they are interchangeable but you have to install brass "freeze" plugs and in the case of using them on a 351 the cylinder head bolt holes need to be drilled out to 1/2" which a machine shop can do when they rebuild them or if you buy them from a supplier they can do. In this case you must change both,the P's flow that much better and they raise the compression a little. I put them on my 60's motor with no problems,but the early heads they replaced were the same volume so the CR ratio stayed the same ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: TX Foilhead
Date Posted: November-01-2013 at 8:59am
| I think they crack from being overheated, pretty common and not a real big deal to fix. You can do it with the motor in the boat if you can break everything loose, it you need to grind any of the bolts off pulling the motor will makes it a little easier. |
Posted By: uk1979
Date Posted: November-01-2013 at 9:14am
Also check out a Q-Bond kit,handy to have as the 2 powders work on plastic or metal, the auto trade use it alot  Good luck with the repair. ------------- Lets have a go 56 Starflite 77 SN 78 SN 80 BFN |
Posted By: kapla
Date Posted: November-04-2013 at 2:11pm
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been there done that...but i went the expensive route..lol std engine 240hp, crack to the outiside port side head on the back of 8 plug. I noticed it cause the carpet got wet...other than that engine ran like a champ...1926 hours...If was to keep the budget I could have gone with the jb weld option...When I got the engine appart it was in pretty good condition, normal ware for the hours it had. but as I was looking to upgrade anyway I ended up with an engine rebuild and new gt40P heads... with the new setup im north of the 310hp... ------------- <a href="">1992 ski nautique |
Posted By: ibiz
Date Posted: November-04-2013 at 3:49pm
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Thanks for the expensive route feedback. I looked closer at the crack. It gushes at WOT, not an issue at lower speeds or idle. But this crack is long - over 2.5 sparkplugs and very hard to get to. JB weld isn't going to work I don't believe. Then the cost of replace two heads is a fair amount, the incremental cost to do the block isn't going to be that much more. Especially, if if we have to start replacing parts after we did into or worse yet the season after replacing the heads. So right now I am looking for a quote to put in a new block and get the GT40P heads. That will set the boat for the next 20+ years. |
Posted By: TRBenj
Date Posted: November-04-2013 at 4:06pm
I am not following this logic... New (GT40p) heads will be $450-650, plus gaskets- so call it $600-800, depending on where you source the heads. A quality rebuilt short block will be 2-3x that much, in addition to the heads. If there is nothing wrong with the short block, why touch it? I'd do a compression test before you touch anything, that will tell you a good bit about the overall health of your engine. If that checks out, then plan on replacing the heads- take a peak around at everything while its apart- but if everything looks good, bolt it back together and go skiing. The only part I'd plan to replace sight unseen "while youre in there" would be the timing set. For $40, throw a quality double roller in there. |
ibiz wrote: