thirdstreettito
Registered Member
How do I check for a dropped cylinder?
CK5
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Check for a dropped cylinder?
- Thread starter thirdstreettito
- Start date
Look under the truck and see if it's laying under there.
Seriously, there is a special compression tester for diesel engines.
Harbor Freight sells a cheap diesel compression tester.
thirdstreettito
Registered Member
Thanks. For some reason I totally forgot about checking the compression. How do I do it?
MaxPF
1/2 ton status
The diesel equivalent of pulling a plug wire to check for a miss is to simply crack the injector line at the injector until fuel pees out. If the cylinder drops out you know that hole was firing. If no fuel pees out when you loosen the line, then you not only found your dead hole, you also found the (extremely unlikely) cause.
The best part is that there are no worn plug boots that zap your a$$ when you pull them off
The best part is that there are no worn plug boots that zap your a$$ when you pull them off
NO spark,yes,but ,instead,there is about 1500 psi of diesel fuel ,that can get squirted right into your bloodstream!..be careful!..
Nah, you have a wrench on a fitting, not your finger over the injectors nozzle.
Rene
Rene
DEMON44
Low-Tech Redneck
The diesel equivalent of pulling a plug wire to check for a miss is to simply crack the injector line at the injector until fuel pees out. If the cylinder drops out you know that hole was firing. If no fuel pees out when you loosen the line, then you not only found your dead hole, you also found the (extremely unlikely) cause.
The best part is that there are no worn plug boots that zap your a$$ when you pull them off
exactly.
way before you do a compression test. you do a cut out test. its the most basic diagnostic procedure. and very useful for find a problem........it won't tell you what it is. but its tell you where it is. start with what easy 1st.
when you crack a high pressure line. the engine is running obviously. but with the wrench on the line nut you only back it off 1/4 turn......1/2 at the most. all you want to do it break injection pressure. if theres no seal at the nut the injector will not fire because the IP cannot build to injection pressure...... the circuit is open. theres no real chance of diesel being injected into your skin. if you keep it to a 1/2 turn. I've done it more times than i can count. you'll get the feel when you do a couple. crack it, engine tone drops, snug it back up, engine picks up again. repeat 7 more times.
you're not really looking for fuel when you do this. you're listening for a change in the engine when you cutout a hole. if you crack a nut and theres no change in the engine. the hole is dead. now you can diagnose further. swap the injector to another known good hole/ problem follows injector or stays in hole? if its in hole. then comp test. and a leakdown test. go from there.
if its just a bum injector, no need to go further with it. replace it and carry on.
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DEMON44
Low-Tech Redneck
NO spark,yes,but ,instead,there is about 1500 psi of diesel fuel ,that can get squirted right into your bloodstream!..be careful!..
1500 psi wouldn't even unseat the injector needle. pop pressures are 3000-5000psi.
those old IDIs run around 14,000psi injection pressure. just so we all know what your handling. no something to be scared of. just respect what your doing.
modern DI pumps are around 18,000psi injection pressure.
and commonrail injection is in 22,000-25,000psi injection pressure.
MaxPF
1/2 ton status
Naw, these old Stanadyne DB2's have a max pressure rating of 6800psi (newer ones are 10,000). typical pop pressure for 6.2 and 6.5 injectors is 1700-2200psi, depending on application. They are relatively low pressure systems. No need for a lot of injection pressure when you have a swirl chamber full of air moving at extremely high speeds
DEMON44
Low-Tech Redneck
ah I was in my bosch book. not a bosch pump.......
ok though still 7000psi......far cry from 1500psi.
ok though still 7000psi......far cry from 1500psi.
