anyone recomend descent leakdown tester?

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pjc360

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I'm looking for a descent leakdown tester to purchase, i dont have to have a real fancy one, but one that will get the job done. I'm having smoke upon de-acceleration and can not figure out why!?!?!? Compression test shows 150psi on every cylinder, there isnt one cylinder thats 149 or 148 they are all 150 dead even and it gets there within 5 seconds of cranking it over with the carb opened up all the way and i'm 4000 feet above sea level. So with such a beautiful compression test i'm baffled as to why its smoking upon de-accleration.....
 
Smoke on decel is almost always valve guides.

I noticed Harbor Freight sells a leakdown tester for about $40, but I'm not sure how "decent" it is. I built one for about that and while I'd be reluctant to say it's accurate to more than +/- 5% it works fine as a basic diagnostic tool. Plenty of info on the web on building your own.
 
I think mine's a Moroso. Snap On's is only $270 online. I don't think I'd get a cheapie one.
But like he said - you may have something that's allowing oil into the chambers that's not the rings.
 
well if this is another clue as to whats going on, i have a non lock up A-518 transmission and when i'm crusing down the highway in overdrive and i shift out of overdrivge smoke comes out my pipes after shifting out of overdrive.....It seems like whenever i'm in a high vaccum situation is when the smoke comes out the pipes. If uit's my valve guides i might as well just put new heads on the wish list, i'm just tired of playing the guessing game and want a leakdown tester to make absolute sure
 
i thought it might be my pcv system, so i put a clear fuel filter on my pcv line and i noticed it helped a little bit with the smoking but didnt take it all away, And the baffles suck on my mopar magnum valve covers, its just shocking to me that an engine with less then 20 thousand miles on it and that passes a compression test with flying colors is burning oil upon de-acceleration.
 
i see an otc leakdown tester for 65 bucks including shipping on amazon, is otc a ok brand?
 
I might just have to bite the bullet and buy new heads.... i really dont think i have piston rings problems when my compression is testing out at 150 psi per cylinder. i'd be shocked if it was piston rings with that good of a compression test.
 
A leak down test prob wont be much helping determing if the valve guides are worn..... also the intake gaskets can cause the same problem as well...
 
really? how do i determine if it is an intake gasket? i did have the intake manifold off last year and i broke a couple intake studs off into the cylinder head and had to drill them out, it was a pain in the ***.
 
how do i determine what is causing this smoking upon deacceleration? i'm going to completly plug off my pcv system and see if that stops it, if it doesnt then what do i do? i was thinking my only option was to get a leak down tester, if compression checks out, and it still smokes even with the pcv system completly plugged off then it dont really leave me with much choice but to get a leak down tester, unless there is a way to tell if my intake manifold gasket is causing this. And is there a way to tell if the valve guides are worn out with the head still on the engine?
 
pjc360 said:
i see an otc leakdown tester for 65 bucks including shipping on amazon, is otc a ok brand?
Click to expand...

I bought the OTC and it is a really nice unit. It looks like it is the same exact unit as the Mac Tools one made in the same place (China) just packaged with different branding. I looked high and low for an American Made Leakdown tester but only came across 3 different styles of the higher-end testers and their designs and manufacture were shared across several different Brand Names. DO NOT buy the Harbor Freight one. Instead of giving two accurate gauges for reading to differentiate the PSI loss the HF has a PSI and then a percentage gauge. It also runs at only 15PSI when the OTC can do 100PSI.
 
i do have a broken intake manifold stud on the passenger side in the middle.... I need to get it drilled out, but i hate drilling broken studs out and the last three that were broken was a huge pita to drill out, but i figured since it was broken in the middle i would get by just filling the hole with silicone untill i got a free afternoon and the motivation to get it out. Could that be causing my smoking upon de-acceleration? Maybe i should take the intake off and drill that broken stud out and throw a brand new gasket on it and get new intake manifold bolts and tighten it down good and tight and see if that siolves it, its worth trying before buying new heads.....
 
To diagnose an internal vacuum leak (either valve guides or intake ports) plug the crankcase breather opening at idle with your hand. You should feel vacuum develop within 1-2 seconds, meaning the PCV system is functioning correctly. The idle speed should not change, if it does that confirms you have a vacuum leak(s) inside the engine (by applying vacuum to both sides of the leak you are equalizing pressures and stopping the leak). If you feel pressure build, the rings are allowing combustion pressure into the crankcase in a greater volume than the PCV can handle, which is a bad thing.

How many miles on the heads? Were the guides and valves replaced, and if so what was their clearance? If you have a leaking port, it should be fairly obvious when you remove the intake. I would do so if for no other reason than to replace the bolt (you don't have studs holding your intake to the heads, you have bolts). If you can't properly torque the intake, or it fits poorly, that could be the cause of your problem.
 
i do to have studs holding the intake to the engine, and this engine was purchased brand new from mopar it's a 300 hp crate 360 magnum it came with a 4 barrell intake manifold, this engine has never had any head work and the motor has close to 20 thousand miles 16 to 18 thousand miles on it. It's always had synthetic oil ran thru it since break inn.
My dad purchased it brand new, and he put it in his hunting truck wich didnt get any miles put on it except for maybe 2 thousand miles every other fall to go hunting, other then that it dont have crap for miles on it. And my intake is a dual plane edelbrock rpm air-gap and no i dont remember seeing a plate under the intake?
 
ok i just started it up and let it idle to normal tempature, then i pulled the pcv hose off the base of my carburetor and put my finger over the hole, there was defanatly vaccum sucking against my finger and my idle dropped a little lower then what it normally idles at with the pcv hose connected at the base of the carburetor. So since my idle speed dropped does that mean i have an issue somewhre?
 
i just dont know what to do here, it's very frustrating i'm about ready to just say screw it and buy new heads,i'm tired of guessing is it this or is it that, feel like i'm just waisting my time chasing this issue. I have done multiple compression checks on it with it at operating temp and every single cylinder hits 150 psi on the dot, so i really dont think i have piston ring problems, and it never smokes when starting it up and it never smokes while at an idle, it only smokes when i back off the throttle after getting on it hard or when i shift out of overdrive it smokes too no matter what rpm i'm at, soon as i shift out of overdrive a blue cloud of smoke rools out the exhaust pipes.
 
chief130 i see that you said close the crankcase breather at idle, i dont have a crank case breather, everything is plugged off except the one opening on the passenger rear side of the valve cover where i hve my pcv valve, i have a crank case breather, but there is no baffle inside my valve cover to protect it from oil, so i figured i might as well not even run it because it will just get drinched in oil withing a few miles and be clogged anyways
 
and the crank case brather i have doesnt have a whole in it to plug.... its just a chrome piece that has some filter like crap inside of it. then i have a crankcase filter also but i wouldnt be able to plug any of those off.
 
New heads? Stab some guide seals in and move on with your life. MAC sells a damn good leakdown tester and I think mine was $130? The beauty of it is that it has what you need to do valve guide seals on the motor.
 
if its the valve guides letting the oil bby what is new valve seals going to do?
 
u might wanna have a shop redo ur heads or put new valve guides in if u dont know what they are. u may want to pick up a services manual a original mopar one and read thru so u atleast know what the parts are.
 
the engine is 10 years old, and another thing i forgot to add i have 18 inches of vaccum at an idle, wouldnt it be considerably lower if i had an internaal vaccum leak? vaccum is pretty steady, but does have a little movementt to it. if that helps anything?
I could replace the intake and exhaust valve seals and see what happens, i have brand new intake and exhaust valve seals for this motor still in the bad never been opened. There are victor rienz seals. I'm just curious about this internal vaccum leak now.... I just dont think thats the issue when i have 18 inches of vaccum at idle, i'd think an internal vaccum leak would lower it to around 12 to 14 and i'd think it'd be fairly unstable vaccum, right?
 
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