Leak down test kit

Coz

Active Member
Oct 9, 2018
443
Boat Info
2008 Sundancer 310
Engines
Merc Mag 350 DTS w/Bravo III
Can anyone recommend a good leak down test kit for occasional use?
 
How do you guys find tdc on each piston?
 
Are you chasing a bad cylinder? I would normally not waste my time with a leak down unless you are trying to identify the cause of a low compression result. The simplest way would be to line up the rotor in the distributor with the post on the cap for the cylinder you are testing. They fire slightly before TDC of compression.
Agree with the don't waste money with cheap amazon crap as the vast majority of it is just that. Offshore cheap crap. For occasional use as you asked in your post, Lang is a decent (made in the US) product. Read their reviews and decide for yourself. No need to dump $600+ on something you will likely only use a few times. Even the cheap crap will identify where the leak is if it doesn't hurt you in the process.
30 years ago I was on the snap-on/mac band wagon and am currently sitting on well over 30g of it. A lot of wasted money there. I'm a diesel mechanic by trade though and the set I posted works fine for the few times I will use it.
 
It's been a while since I did one of these, I think I got mine from Napa, and was happy with it; revealed a bad head gasket that was replaced under warranty (Jasper long block).
 
How do you guys find tdc on each piston?
You just need to find it for cylinder #1. Use the timing mark on the crank pulley. When it’s lined up, either #1 or #6 is at tdc of the compression stroke. Removing the distributor cap will confirm which one.

Now mark the crank pulley in 90° increments.
After that, each 90° movement of the crankshaft will bring the next cylinder in the firing order to tdc of its compression stroke.

1-8-4-3-6-5-7-2
 
Very long story. Been chasing low rpm on one engine for 2 years. Done and tested bout everything except leak down test.
 
You can pretty much do the same thing by chucking up a 100lbs of air to the plug hole and listen where the air is coming out and at what intensity.
 
Leak down won't tell you head or rings, just overall health. To test for for what your looking for. First do a compression test on each cylinder and log it. The spray marvel mystery oil in the cylinder's, enough to coat the wall's. Do another compression test. Big changes in a cylinder means the rings or cylinder could be scored. Minimal change possible vales are worn/burnt. Pay particular attention to 3,4,5,6 these typically go first with mushroomed exhaust valves.
 
Pulled drives today and turns out they’re geared different. Swapped ‘‘em and problem followed. At least I didn’t waste time doing a leak down test
 

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