LEAKDOWN TEST QUESTION

[man-of-war]

LEAKDOWN TEST QUESTION

I got my hands on a snapon leakdown tester. befor preforming the test do i have to loosen all the rockers? Get the piston up to TDC on the compression stroke . The reason why im asking about loosening the roller rockers is because the michanic that built the engine said thats the way a leakdown test is done with hydrolic lifters.just wanted to make sure THANKS

 

[Bondo]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

I can't think of Any Reason to do That..........

 

[bigbrownbuku]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

even motors with hydraulic lifters need both valves closed at some point. just get the cylinder to be tested to tdc<br />(compression stroke), test, move on to the next.

 

[man-of-war]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

This mechanic is playing the a$$ with me. I'll have to take the boat to Bristol Marine and have them do it professionally. I will get the results from the test on their letterhead in black and white and present it to my rebuilder. Someone rebuilding the engine again.

 

[4.3sunbird]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

to be sure the valves are completly closed they must be backed off <br /><br />doing the leakdown at tdc is most important but I like to run the piston down in the bore some and test also <br /><br />you could have great seal at tdc but have scrathes down in the bore from the piston skirts <br /><br />as long as its good at tdc a natrually asperated engine would be fine running wise but will still be slightly down on power if leaking more as it goes down the bore.. when forced induction is added it needs to have good seal all the way down the bore since you have so much stuffed in there you still have high cylinder pressure thru the entire power stroke <br /><br />I just did one I still had 2% leak at tdc but 70% by time it reached bdc <br /><br />teardown shows scuffing from the piston skirts so fine I cant feel them with my fingernail .. but the tester dont lie <br /><br />you can check for valve seating also .. just hook your air line strait to the hose that goes in the spark pluhg hole then listen at the intake and down by the exhaust for air coming out <br /><br />I also use a snap-on tester its simple and works good

 

[Don S]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

IF, you loosen the lifters, then you can put the piston at the bottom of the cylinder. <br />It is not necessary to loosen the lifters if you set each piston at exactly TDC on that cylinders compression stroke.

 

[man-of-war]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

Thanks guys, I ask one question and got four answers that were all the same, from difrent michanics across the world.I'll print and present this post along with the leak down test. thanks again

 

[rodbolt]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

well you get two from me.<br />depending on access sometimes I will fight it at TDC, if ya miss TDC by two degrees it will rotate the moror unless you have a way to lock the flywheel. if the rockers are removed it does not matter much. some engines require removal of the manifolds to remove rockers and others are simple to lock at TDC compression stroke.<br /> if ya do it 20 years or so its simple.<br /> but you wont believe how many techs I have seen get whacked in the head by a breaker bar doing a leakdown . so far I have not but I reckon its coming.

 

[man-of-war]

Re: LEAKDOWN TEST QUESTION

Re: LEAKDOWN TEST QUESTION

yes in order for me to remove the rockercover, the exhaust manifold has to de removed.the boat's going in for the leakdown test tomorrow,i dont wana get whacked in the head..Don's was right about the gas in crankcase,i fix nothing.i spoke to the carb tech today and he's going to use a smaller size jet in the primeary.if that does not work, could a stuck or leaking valve cause the gas to get into the crankcase??