Rent one, build my own, buy a cheap one (Harbor Freight, eBay, etc) or buy a good one?
I don’t really have a lot of money to spend since I just bought a compression tester. But my bike badly failed the compression test, so it’s on to leakdown to know if it’s valves, rings/cylinders, or both. I will probably use this tool very little. Almost never. I’ll check the cougar and bronco and bike of course, but probably not touch it again for years.
I hesitate to rent, cause I feel like that’s sorta throwing money away. Making my own should be cheap and all, but I wanna be sure I’m getting good results and all.
So it’s a dilemma. Anyone have any recommendations here?
Many tools are available from auto parts stores for free as loaners. They put it on your credit card, and reverse when you bring it back. Perfect for things you only intend to use once.
Oh man that sounds perfect. I’ve heard of that before but never done it and didn’t think to do it here, which is a perfect application. Gotta check my local NAPA and see if they can hook me up. That would be perfect!
Built my own from a Hot Rod or Car Craft magazine article many, many years ago. Broke down and bought a Summit branded a couple of years ago.
Very useful tool if used correctly (checked at TDC with rockers loosened) however won’t indicate worn oil rings.
The 428 is out of the car and sitting on a pallet. I need to perform a leakdown test but I have never done one before. I borrowed a leakdown tester from my industrial neighbor. It is a MAC Tools setup with two gauges and the adjustment valve. I know all about hooking it up but I need someone experienced with Cobra Jets to help me measure it properly.
I found cylinder #1, front of engine, passenger side and put it at TDC per the harmonic balancer and a screwdriver down the plug hole. I set the left gauge at 100psi and read the right gauge to calculate the percentage drop. I got a right gauge reading of around 84psi so I have that one. Now, the question of firing order comes to mind; I believe it is 15426378. To get to cylinder #5, I wrenched the front pulley bolt (righty-tighty) to get to TDC and verified with screwdriver in plug hole. I got a very low reading like 18 pounds or so.
So what would be the normal procedure for performing this test on an engine that is sitting on a shipping pallet and has not really been started in over a year? I have a battery connected to run the starter motor and we have turned the motor over about a dozen revolutions to get oil moving.
BTW, compression tests showed a value of between 176 and 184 pounds for all cylinders with an average of 180 pounds.
I need some technical guidance and Kentucky windage help with this.
I did the test. I used 90# as the source pressure and here are the readings for each cylinder:
1 73#
5 76#
4 75#
2 77#
6 70#
3 75#
7 78#
8 75#
There could be some variations caused simply by the fact that we did not use a dial indicator to verify TDC on compression stroke but It looks pretty darned good!
I would squirt some oil in each cylinder. Rotate the engine a couple turns and then do it.
From what I am seeing your results look decent. It doesn’t tell you anything about whether the rocker arm shafts are worn out or if the valve guides are shot. Also the valve springs, if they are 50+ years old, are likely fit for the dumpster. If it was me I would get a valve job done on the heads while the engine is out. Then you can look at the bores to see if anything needs to be done there. Maybe look at a few main and rod bearings too.
Disassemble the rocker arm assemblies and make sure they are in good shape. Clean inside the two rocker shafts to remove sludge if the shafts seem OK.
From what I have guessed so far, the heads are painted a reddish color and when I had the car, they were Ford blue. The heads also have the vin (well, driver’s side) stamped in them and there is evidence of blue rtv gasket sealer on the intake manifold edges. My guess is that there was a top-end job somewhat recently (measured in miles since, not years since). I’ma pulla the valve covers anyway so I can always look at that. Also pulla da’ oilpan and look at bottom end.
A leakdown test is measuring the efficacy of the valve to valve seat sealing and the piston ring to cylinder wall fit.
A leakdown test has no way to tell if the valve guides or valve oil seals are any good. Or if the crank / rod bearings are any good. Or if the engine is packed with sludge. Or if the rockers and rocker shafts are worn.
Yes, my compression looked great. But valve oil seals were leaking oil into cylinders when shut down causing blue oil smoke on start up. Bores and rings were fine. Timing chain was loose, so new timing set. And we found the middle main bearings were pretty worn for 63k miles. Lots of start ups over 50 years.
, on the loan-a-tool, especially if you aren’t going to use it for years.
