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Leakdown Tester


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This is a "How-To" on making your own leakdown tester. This is going to explain step by step exactly what you need to do in order to make a homemade leakdown tester.


First. You will need to measure the inner-diameter of your intake. This is the size of PVC pipe that you will need to buy. Get as close to the actual size as you can. Without going over.




Second. You will need to measure your exhaust outlets inner-diameter to find out what size freeze plugs you will need. Same thing. Get as close to the size that you need as possible without going over. NOTE: You will need to get the size that goes up to the size that you need. For example; if you have an ID that equals 1 3/4". You will need to get the size that is 1 5/8" to 1 3/4". The one that is 1 3/4" and bigger. Is going to be too large for you.


Then you will need to go out and get all the supplies. All of these parts should be fairly easy to come by.




Expandable freeze plugs. Purchased at Advanced Auto Parts.




1 1/2" PVC Schedule 40 pipe. Purchased at Lowes.




Two 1 1/2" PVC Schedule 40 caps.




Tire pressure gauge. NOTE: Needs to be easily readable at 6PSI. Purchased at Advanced Auto Parts.




Metal Tubeless valve stems. NOTE: The ones that have a nut are easier to get tighter. Purchased at Advanced Auto Parts.




Handy Pack of PVC cement, too include primer and cement. Purchased at Lowes.




Now. On to the fun. Measure out about 3 inches of PVC pipe. Mark to make a cut.




Then cut it. Doesn't have to be perfect either.


Now. Measure another 3" section out. And cut that also. Still doesn't need to be perfect. Should have two now.



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Set the two pieces of PVC pipe on a flat surface. Pick a side that you want to have the caps on. Use the purple primer out of the Handy pack to prime the ends of the pipe. The brush is inside the can of primer. Might be hard to open the first time. No big deal.




Do the inside of the caps also.




Then apply some cement the same way. Be careful with the cement. You do not need a lot. When you are done with applying the cement on the outside of the pipe and on the inside of the caps. You should put the caps on top of the pipe pieces. Press down as hard as you can to make sure to get the best seal on the cement.




Ok. The tire gauge that I bought needs a little modification. So, we are going to open it up and look at the bottom.




The little brass flat head screw in there needs to be loosened and removed. When you loosen that screw, you'll notice that the outside came undone too. Unscrew the whole thing. Including the outside cap. Should look like this when completed.




Now that is all taken care of. We can move onto the drilling. You are going to have to find a drill bit that is small enough for the end of the tire gauge. Then you are going to drill the end of one of the caps with this bit.




Should look like this.




Test fit. The end of tire gauge should now have a threaded end on it. You do not want to go so big that you can not thread it in to place in the cap.




Take the tire gauge back out. Prime and cement the hole.




Now take the tire gauge and screw it into permanent place. Make sure no cement gets on the inside of the pressure gauge.




Done with one!

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Now onto the second one.


Take your valve stem and take it apart. Should look like this.




Now, take the other pipe with cap and drill it the same way that you did the first one. With a bit that is slightly smaller than the valve stem threads.




Should look like this.




Test fit. Screw the valve stem in the opposite way, so that you know the hole is not too big for the stem.






Take the stem out and prime and cement the hole.




Now, slide the valve stem into place on the inside of the pipe. Screw it into place. Do not get cement on the top or bottom of the vavle stem. Then all you have to do is, screw the washer and nut back on the top of the stem. NOTE: If you can fit the other black bushing on top of the cap around the valve stem, I strongly suggest you do. It will only help. Not totally necessary though.




Looks like this when you look inside the pipe.




This is what they look like thus far.




Use a little bit of sealant on the holes we drilled.



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Looks like this now.




Done with the leakdown tester!!!


Now for the process.


Put the expandable freeze plugs in the exhaust outlets and tighten them down!! This is very important. They should be air tight!




Take your pipes and put them into the intakes. NOTE: I used some more sealant where the caps stop on the pipe. Not necessary.




Hook up your tire inflator. Inflate to 6PSI only!




I use an electric tire inflator made by Bell to keep pumping air in, so that I can find leaks. If your motor does not hold the air. Take a spray bottle of warm soapy water, re-inflate to 6PSI and spray around different parts of your motor to find the leak.



Hope this helps you. Most of this info came from my buddies off this site. Chad, Austin, Dave and Shayne. Thanks a lot for all your guys' help.


If anybody sees anything wrong with this info, let me know ASAP! So I can get it right!

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This is VERY similar to the one I had made.. Little different config but overall the same idea..

The freeze plugs or whatever I found didn't work that well.. Had a hard time getting them sealed and they would try to push themselves out.. Also on the valve stem and and guage side this is ok but people NEED to be aware as to not over pressure it. Lead to bigger and badder problems..

I ended up buying a kit(wasn't the greatest idea either as the quality was sub par) and it has the hand pump and stuff which is nice but also had a good alternative to those freeze plugs..


Otherwise nice little write up..


Here is a write up that was done a long time ago and I always refered to..




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Great write up man. I wish you would have posted this a couple days ago before I read through 20 pages of old threads :down: .

I have a question. The tire gauge you have looks like it has an air release button on it. So doesnt that hold the pressure on the gauge until you hit the button? Or did taking out the bottom of the gauge disengage that pressure release?

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No, I get what he's saying. The guage will not show if your engine has a leak. The guage holds all the pressure until you hit the pressure relief button. There could be 2psi in the engine, but the guage still reads 6psi, because of the button. You need a guage that does not have that relief button.

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