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Bullzybull

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Re: Ford 460 Low compression on all port side cylnders
« Reply #25 on: February 22, 2016, 10:03:06 PM »
Hi guys, I haven't had any time to diagnose the boat yet with work and a full kitchen remodel at the house it's been rough finding the time. But I have made notes with all the info and suggestions you guys have made. I really really appreciate it. I'm hoping to get some new results from the compression test. I will do a cylinder leak down test if needed depending on the results of the compression test. I'll also double check the casting numbers on the heads that's honestly something I would have never thought of. I'll try to have some solid results by sun or mon.


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Bullzybull

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Re: Ford 460 Low compression on all port side cylnders
« Reply #26 on: February 28, 2016, 12:59:11 PM »
Ok I got some results from the compression test. Turns out Like probably everyone on here suspected. I did the test wrong!  Shocker. All of the cylinders gave good pressure but #8. It came back at 80psi. Besides that. Boat sounds right. Fires up and runs great. Ran the boat for a good 15-20 mins on the hose and temp stayed low around 120. Oil looked good. Hoping to get a leak down tester tomorrow from Harbor freight. I know that should give me a better idea of what's going on. With the info that I have now though, do you think it would be OK to run with that one cylinder at 80?
Thanks again for all your help and feedback!


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GT Jets

  • Karma: +192/-0
Re: Ford 460 Low compression on all port side cylnders
« Reply #27 on: February 28, 2016, 01:08:52 PM »
With the info that I have now though, do you think it would be OK to run with that one cylinder at 80?
Thanks again for all your help and feedback!


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Just going to say it.

No.

It really is going to depend what the leak down test comes down to,  but two things going through my mind.

One,  if it's a rusty cylinder wall,  eventually it will have zero compression. It could also be a stuck ring,  ultimately cutting away at the cylinder. May be an easy fix now but an expensive fix after it goes all the way.

Two, if it's a valve issue,  as hard as these engines run,  it could ultimately overheat the valve and drop it into the cylinder,  with a great chance of destroying the entire engine.

I honestly think you should investigate further. That's why a compression test is done,  to try and prevent small problems from becoming catastrophic.

Good luck.

GT
« Last Edit: February 28, 2016, 02:44:58 PM by GT Jets »
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

FordLover

  • Karma: +72/-0
Re: Ford 460 Low compression on all port side cylnders
« Reply #28 on: February 28, 2016, 02:18:27 PM »
Seriously, dont mess around. I know first hand what a dropped valve does. Pure carnage. Turned that engine into no better than an anchor.
« Last Edit: February 28, 2016, 02:48:51 PM by FordLover »
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Bullzybull

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Re: Ford 460 Low compression on all port side cylnders
« Reply #29 on: February 29, 2016, 05:59:23 PM »
Alright, I just did a leak down and I had exactly 20% loss which is in the green on the gauge. Good. So I decided to redue the compression test and I had 120psi. I don't know. Everything seems to be fine now.

All I know is this was a great lesson for newbie on the importance of PROPER diagnostic checks and big shout out to all you guys for all your help especially Ghett0man.

Thanks guys.


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Bullzybull

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Re: Ford 460 Low compression on all port side cylnders
« Reply #30 on: February 29, 2016, 06:01:13 PM »
Also I plan on taking a trip to Elsinore tomorrow to see how the boat does under way. I'll post any info that comes from that.


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Bunger

  • Karma: +6/-0
Re: Ford 460 Low compression on all port side cylnders
« Reply #31 on: February 29, 2016, 07:53:10 PM »

Also I plan on taking a trip to Elsinore tomorrow to see how the boat does under way. I'll post any info that comes from that.


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Didn't have time to read all the way back but did you check your pump? Could have sucked something up clogging the cooling line and could have fouled up your pump/impeller . Just a thought


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Bullzybull

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Re: Ford 460 Low compression on all port side cylnders
« Reply #32 on: March 02, 2016, 10:38:52 PM »
Yea I think that's definately what caused the over heat. Just wanted to make sure no major damage had occurred. So when I got bad results on diagnostic tests it made me worried. But turns out I was doing the compression and leak down wrong. Motor is good to go. Got lucky.


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