Re: Oil Pan Gasket - While I'm in there...
Posted: Tue Sep 10, 2024 1:42 pm
My experience --
The leak-down test demands more air pressure than a Motive bleeder can generate, and more volume than you are willing to supply with the hand pump.
The leak-down tester uses a couple pressure gauges with a calibrated orifice between them. The air on one end, hose to spark plug at the other end. Since you are 'calculating' leak-down as a percentage, using 100 PSI on the upstream supply side lets you read downstream pressure directly as the percentage (actually 100 - minus the gauge reading). So your compressor with a decent pressure regulator will be essential. For the connection to the spark plug, I use the hose from my compression gauge kit, one with a quick-disconnect fitting on the gauge end.
You'll want to lock the motor at TDC compression on each cylinder as you test. Air in the cylinder will cause the crank to spin if it isn't right at the top of stroke. The flywheel lock you use while loosening the crank bolt will be perfect.
All that said, a set of good compression readings will usually tell you more about the actual condition than a leak-down test. I depend on a leak-down test for engines I can't warm up and test for compression, like a used engine on a pallet. I can listen for where air is leaking out too, something that would help with that used-engine assessment.
For injector cleaning, assuming I don't need to replace filters or pintle caps, I can clean them myself on or off the car. Off the car, I use a cannister with cleaning fluid in it, and add compressed air at a fitting on top. The bottom has a hose that happens to fit over the top of the injector with a small clamp. I put the injector in a large glass cylinder (I use a cheap flower vase...) and throw a towel over the top to contain the spray. As Tom suggests, a 9V battery is plenty to open the injector. An actual 12V is probably safe for pulsing with low duty cycle. The 9V battery is cheap and easy, and safe to just keep it open for cleaning.
I've found that Berryman's B12 from Wal-Mart is a good cleaner for my casual needs. It was $5 a can yesterday on the local shelf. The car will run OK on the same chemical, so I use it for on-car cleaning too. Same rig, but I connect it to the front end of the fuel rail with a modified rail cap. It's drilled and tapped 1/4" for a fitting common on GM cars, and the ball behind the fitting is replaced with a 1/4" brass tubing ferrule inside. Return hose to the tank gets pinched, and air pressure equals fuel pressure in the cannister. fuel pump fuse comes out. My car gets good fuel, but doesn't see enough driving to reliably keep injectors spotless. The on-car method is easy and inexpensive, and it works for my car and my needs.
The B12 has a hefty dose of toluene, methanol, and a couple other solvents including isopropanol. Causes cancer and brain damage on skin contact, faster via eye or nasal/oral contact. Very flammable, and the mist is explosive. Keep the battery and switch well clear of the injector itself. And everything is done outside, away from friends, toys and structures that don't need to burn. They sell an even more intense cleaning product called IIRC B60 for barn-find cars and seriously neglected fuel systems. I have never needed it, but after reading some descriptions I'd be way tempted to try it in a longer-stored CIS/K-jet car before even turning the key the first time. Best to get varnish and deposits out as much as possible before clogging the rest of the system pieces.
The leak-down test demands more air pressure than a Motive bleeder can generate, and more volume than you are willing to supply with the hand pump.
The leak-down tester uses a couple pressure gauges with a calibrated orifice between them. The air on one end, hose to spark plug at the other end. Since you are 'calculating' leak-down as a percentage, using 100 PSI on the upstream supply side lets you read downstream pressure directly as the percentage (actually 100 - minus the gauge reading). So your compressor with a decent pressure regulator will be essential. For the connection to the spark plug, I use the hose from my compression gauge kit, one with a quick-disconnect fitting on the gauge end.
You'll want to lock the motor at TDC compression on each cylinder as you test. Air in the cylinder will cause the crank to spin if it isn't right at the top of stroke. The flywheel lock you use while loosening the crank bolt will be perfect.
All that said, a set of good compression readings will usually tell you more about the actual condition than a leak-down test. I depend on a leak-down test for engines I can't warm up and test for compression, like a used engine on a pallet. I can listen for where air is leaking out too, something that would help with that used-engine assessment.
For injector cleaning, assuming I don't need to replace filters or pintle caps, I can clean them myself on or off the car. Off the car, I use a cannister with cleaning fluid in it, and add compressed air at a fitting on top. The bottom has a hose that happens to fit over the top of the injector with a small clamp. I put the injector in a large glass cylinder (I use a cheap flower vase...) and throw a towel over the top to contain the spray. As Tom suggests, a 9V battery is plenty to open the injector. An actual 12V is probably safe for pulsing with low duty cycle. The 9V battery is cheap and easy, and safe to just keep it open for cleaning.
I've found that Berryman's B12 from Wal-Mart is a good cleaner for my casual needs. It was $5 a can yesterday on the local shelf. The car will run OK on the same chemical, so I use it for on-car cleaning too. Same rig, but I connect it to the front end of the fuel rail with a modified rail cap. It's drilled and tapped 1/4" for a fitting common on GM cars, and the ball behind the fitting is replaced with a 1/4" brass tubing ferrule inside. Return hose to the tank gets pinched, and air pressure equals fuel pressure in the cannister. fuel pump fuse comes out. My car gets good fuel, but doesn't see enough driving to reliably keep injectors spotless. The on-car method is easy and inexpensive, and it works for my car and my needs.
The B12 has a hefty dose of toluene, methanol, and a couple other solvents including isopropanol. Causes cancer and brain damage on skin contact, faster via eye or nasal/oral contact. Very flammable, and the mist is explosive. Keep the battery and switch well clear of the injector itself. And everything is done outside, away from friends, toys and structures that don't need to burn. They sell an even more intense cleaning product called IIRC B60 for barn-find cars and seriously neglected fuel systems. I have never needed it, but after reading some descriptions I'd be way tempted to try it in a longer-stored CIS/K-jet car before even turning the key the first time. Best to get varnish and deposits out as much as possible before clogging the rest of the system pieces.
