LEAK DOWN TEST RESULTS

[man-of-war]

The test from bristol marine did show leakage from ALL exhaust valves.they wanted to fix the problem for $1600.00, which i said no.I got the report from Bristol and gave it to the michanic last week.finaly he called today for me to bring the boat down to do another leakdown test,all readings were 80's and 30's the exhaust valves wont shut. he removed all rockers and used a hammer to tap the valve stems ,no change in readings. i have to take the heads off, and take them to his shop tomorrow.still cant get a reading off the rings until the valves are fixed.

 

[Dunaruna]

Re: LEAK DOWN TEST RESULTS

When you get the heads off, can you post a pic or 2? (before you give them to the mech).<br /><br />Just curious.

 

[man-of-war]

Re: LEAK DOWN TEST RESULTS

will do,i also want to see if all the pistons were changed.or if he just replased the 2 that were damaged.

 

[man-of-war]

Re: LEAK DOWN TEST RESULTS

This is a quote from Bondo:<br />--------------------------------------------------------------------------------<br />If you haven't Retuned the Carb. to compensate for the freer flowing exhaust,..........<br /><br />You're Probably running Lean,.. Atleast part way thru the rpm band,......<br />Maybe running Lean from Idle to WOT,.........<br /><br />--------------------------------------------------------------------------------<br /><br />Would having the exhaust valves stuck open also hampen performance and make the engine run lean? And would this cause me to get false compression readings?<br />Thank you

 

[Bondo]

Re: LEAK DOWN TEST RESULTS

If the Exhaust Valves aren't Closing,......<br /><br />Rich or Lean is irrelevant,.......<br /><br />You've got No Compression......

 

[man-of-war]

Re: LEAK DOWN TEST RESULTS

I scraped the heads off and this is what I found. Three things that caught my eye were: between cyclinders 3 and 5 has a leak .... I found vertical scratches in the cyclinders (not digs or gauges but like sandpaper wear) .... Bent # 6 Pushrod. On some of the pictures at the end I did a water leakdown test and all the exhaust valves are leaking. I wish I had more light so you can see the amount of droplets. Some of them were 6 second drops and some were 2 seconds. I took the heads in today, they scraped it all down and resurfaced everything. If the mechanic refuses to install the heads I'll need your help with the torque specs. I told him about the scratches on the cyclinder walls and he said let's take it one step at a time. I know the rings are busted and this is just double work.<br /><br /><br />Intake Rebore - Another angle<br /><br />

<br /><br /><br />Leak Between Cyclinders 3 and 5<br /><br />

<br /><br /><br />Leakdown Test<br /><br />

<br /><br /><br />Leakdown Test - Another angle<br /><br />

<br /><br /><br />Leakdown Test - Water Droplets<br /><br />

<br /><br /><br />Leakdown Test - Water Droplets<br /><br />

<br /><br /><br />One of These Rods is Not Like the Others<br /><br />

<br /><br /><br />Pushrod Brand?<br /><br />

 

[Dunaruna]

Re: LEAK DOWN TEST RESULTS

Bent pushrod, leaking ex valves and possible compression leak between cyls - all after 5 hours. If the original mech won't play ball, you either need to cut your losses and find a new one (to do the COMPLETE job) or seek legal advise, IMO.<br /><br />Aldo

 

[man-of-war]

Re: LEAK DOWN TEST RESULTS

What would cause the push rod to bend?

 

[steve n carol]

Re: LEAK DOWN TEST RESULTS

Contact between the valve and the top of the piston would cause the pushrod to bend. This could be caused by a lot of circumstances, one being 'valve float'. Were the heads cracked? pistons cracked, nicked or marred,<br />due to them (the pistons) contacting the head?<br />Pistons contacting the cylinder head/s can also bend the connecting rod/s...sl

 

[Dunaruna]

Re: LEAK DOWN TEST RESULTS

or the mechanic tightened down the rockers too quickly, didn't give the lifters time to bleed.

 

[man-of-war]

Re: LEAK DOWN TEST RESULTS

ill take a proper look at the piston in the morning.thanks

 

[man-of-war]

Re: LEAK DOWN TEST RESULTS

the heads go back in tomorrow,were doing a leakdown test again, what's the maximum leakage allowed per cylinder. thanks

 

[javsam]

Re: LEAK DOWN TEST RESULTS

15 percent I believe.<br />javsam

 

[rodbolt]

Re: LEAK DOWN TEST RESULTS

dude<br /> anthying past 10% on a fresh m,otor is junk.<br /> if your MOchanic is using a running method of valve train adjustment,find another mochanic.<br /> once you quit splattering about and wish to get serious post to me or maybe DonS will chip in. most the other advice you have been given is by persons that read hot rod magazine but have little practicle experience with you motor.<br /> its almost to the point I will ask you to email me with a phone#.<br /> a bent pushrod WILL NOT cause a valve to leak. however a piston that contaccts a valve can bend a valve and a pushrod.<br /> <br /> best advice is, keep it simpmle S.

 

[Don S]

Re: LEAK DOWN TEST RESULTS

rodbolt<br />I've given up on a few posters.<br />You just can't teach how to be a mechanic on a forum. You can give a mechanic some ideas, and something to check, but you can't make a mechanic out of someone that doesn't know the basics, or how and why an engine works or doesn't work. It's possible to help with tuneups, oil changes, gear lube changes, alignments, gimbal bearings etc. etc. but when it gets into engine and drive rebuilding, if you don't know what/why to do, stick with cars, not boats. It's a cheaper tow and a lot less expensive.<br />I tried the email and phone# thing before, and soon regretted it.

 

[man-of-war]

Re: LEAK DOWN TEST RESULTS

Thanks rodbolt,for the offer and thanks Don S for your advice as well. I've tried to cure this gas in crank case problem but failed. I've replaced fuel pumps 3 times and had them pressure tested for leaks after each run - the pumps are good. Next the carbs, 3310 HOLLEY - This carb has been rebuilt twice this year and flowbench - nothing wrong with it. EDELBROCK 1410 MARINE - we've tried different metering rods and jets with no success stoping the gas in crankcase. This carb was flowed as well........next is the INTAKE MANIFOLD AND THE THUNDERBOLT IV AND COIL.<br /><br />I spent the day installing the heads and assembling the engine, got it done last night. Started it and ran it for 10 min. It goes back to my monkeymechanic on Monday to finish the leakdown test. I also asked him about the bent pushrod and he said the engine probably backfired?