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| Pulling Cylinder head on Volvo V8 in Horizon https://www.smwebhead.com/phpBB3/viewtopic.php?f=3&t=6848 |
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| Author: | DaleG [ Sun Nov 07, 2010 3:18 pm ] |
| Post subject: | Pulling Cylinder head on Volvo V8 in Horizon |
I am curious if anyone has personally pulled the cylinder head from a Volvo V8 -- (or Mercruiser V8 for that matter) in a Horizon. Did you do it with the engine still in the boat, or did you decide it was easier to remove the entire engine? I had an undiagnosed leak at a riser gasket which led to an engine miss. I never had any other symptoms before the engine miss. I replaced the risers (and plugs etc)and I have run the engine for a week on vacation. and several outings. It runs OK, but it is not developing full power, so I knew there was another issue. I took compression readings today and number 2 shows only 50 psi. -- (all the rest are OK at about 175-185 on a cold engine with about 325 hours) The head must therefore come off. I would suspect a valve/valve seat issue. I have done this sort of things many times through the years on cars and boats so correcting the problem is not the issue. It is just deciding the best/easiest way to go about doing it. |
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| Author: | LouC [ Sun Nov 07, 2010 8:00 pm ] |
| Post subject: | Re: Pulling Cylinder head on Volvo V8 in Horizon |
I think if you are just removing the head you could leave the engine in the boat, but I'd get some help, they are heavy and you have to lift it up pretty high to get it out of the boat. The main thing when taking it apart is to clean the engine really well so no dirt gets in when you start taking stuff apart....I wonder if it would be worth it to try to get that sticky valve loose before removing the head, I have heard of people doing this with some success, by using a top engine cleaner... you might want to try this and then repeat your compression test on a hot engine, with the throttle wide open and the ignition coil grounded. There can be a difference between cold and hot compression test results. I recently did a compression test on my old 88 4.3, the cylinders ranged from 165-185...... |
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| Author: | Aussie_Horizon_190 [ Sun Nov 07, 2010 8:34 pm ] |
| Post subject: | Re: Pulling Cylinder head on Volvo V8 in Horizon |
+1 to Lou's comment. Much like a car, taking the head/s off in the boat will be easier than lifting the motor - definately the way I would go. Worst case is that you'll end up having to pull the motor as well, but it will be some 40 pounts lighter wothout the head! |
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| Author: | DaleG [ Tue Nov 09, 2010 2:20 pm ] |
| Post subject: | Re: Pulling Cylinder head on Volvo V8 in Horizon |
thanks for the replies --- but I think I am leaning toward pulling the entire engine at the moment. I would pull the drive first, and probably do the gimbal bearing there. Then when the engine is pulled do all the other things around it like cleaning the bilge, looking at a small hydraulic leak -- etc and with the engine on a stand I would not be leaning over trying to do things. Now I just have to figure out the best way to get the engine out of the boat --a simple engine hoist will not hack it (been there-done that) --- I will need either a bigger hoist than normal, a forklift maybe, or a small skid-loader with a boom -- or something like that. I might even have to build my own gantry. |
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| Author: | DaleG [ Mon Nov 15, 2010 12:01 pm ] |
| Post subject: | Re: Pulling Cylinder head on Volvo V8 in Horizon |
brief update -- have not decided how to remedy my low compression reading on one cylinder, but I did confirm a few things. First -- I did a wet compression reading (squirted oil in cylinder) and retested -- compression only went up 5 psi -- so problem not probably in the bottom end of the engine --good news. Second --- removed rocker cover and watched valve actuation -- lift seemed good/pushrods straight/no visual obvious problems -- etc -- did not check valve lift with dial indicator but considered it. Next -- put compressed air into cylinder after I loosened both intake and exhaust rocker studs (just to make sure valves are closed) Result --loss of air/noise on exhaust valve side. Conclusion -- probably a bent(warped) valve or maybe a valve seat issue on #2 cylinder. The head still has to be removed to correct the problem, but I have a lot more confidence that the exhasut valve is the issue and I won't get a surprise when I pull the cylinder head. Probably be after xmas when I finally I finally decide to tear into the engine. |
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| Author: | Lakebum [ Mon Nov 15, 2010 1:29 pm ] |
| Post subject: | Re: Pulling Cylinder head on Volvo V8 in Horizon |
Sorry to hear that, I went through the same thing last fall on my port side engine and then the starboard this spring. Too much coincidence, but that's part of boating. It was pretty tight but I managed to get the heads off without removing the engine. Both times it was a stuck/burnt/tuplided valve. The best advice I got was: if you're tearing down 1 side, you might as well do both. On both engines I had 1 bad cylinder (0) compression. But after numerous suggestions I took both heads off and found the same thing starting to happen on the other side. I think the worst part of the job was cleaning the old gasket off the block before putting everything back together (must be spotless). Good machine shop should magnaflux, reface and valve job for less than $300/both heads. Valves and gaskets maybe $150-$200. I found a lot of engine downloads from Iboats and made friends with some go fasts folks. Good luck |
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