Compression Test/ Leak Down Test Info Req,

[rustam54]

@Xulfiqar.

Sir i did some resistance checks and following are the results.

Cylinder 1 (Longest Cable) = 9.66 KOhms
Cylinder 2 (Almost Same Length) = 9.36KOhms
Cylinder 3 (Closest to distributor) = 6.34KOhms

Coil to Distributor = 11KOhms

Note: The "coil to distributor" and "cylinder 3" cables are of almost same length.

Ignition Coil Testing:
Between Primary Contacts = 1.2 Ohms
Between each primary contact and secondary out = 14 KOhms

Note: The meter was reading almost 7.3 ohms with only meter cables shorted. I read 8.5 on primary side. So concluded = 1.2 Ohms. I could'nt get any value between Secondary out and coil mounting base. I thought that one end might be shorted to chassis but it wasn't.

Also the cables were removed and the distributor points were checked. All showed zero resistance.

So any ideas?????

[Xulfiqar]

your cap is scratched up - it will create tracks. replace it, the cables resistances are acceptable. the ignition coil primary resistance should be about 0.7 ohms though. The secondary one is in spec though.

Please do check the ground cables from the battery, and check the voltage drop to the cylinder head.

[rustam54]

Okay.. i'll check the ground cables as well. By the way, dont you think one HT cable is off spec???? 6.34KOhms compared to 9.35K Ohms.

For the coil resitance, i should mention as well that the tests were done on a hot engine. May be it could be less on cold engine. However I'll re-check that as well and let you know.

[rustam54]

Alright fellows.

The original problem has been identified and rectified accordingly. The culprit was "retarded ignition timing". You couldn't feel it at medium engine load.

Previoulsy it was 13.8 Deg on CNG and 8 Deg on Petrol. Now the advancer has been moved to almost extreme anticlockwise and gas re-adjusted. I am not sure what timing is right now but i would get it confirmed on weekend and post it here for future reference.

The previously lagging and jerking rpm range is now smooth.

I must admit, it was partial my fault for not looking into it in the past. I once advanced it a bit but didnt adjust gas and then reverted back. The guy who fixed it, didnt say anything about valves or so. He just took a test drive and pin pointed in (say) 60 seconds. Another 30 to fix it.

Lastly, i would like to thank all the members who contributed to the thread. Especially Mr. Xulfiqar and Mr. Capsat. Thank you gentlemen for your kind support. Looking forward to your guidance in future as well.

Best Regards,

Nauman

[ridwanshaikh]

can u help me i have cultus 2009 model and white smoke is coming fro cylincer when its starts and when i acclerate it the smoke grows and little oil is coming in cylincer and some krrrr krrrr noise is also coming in engine can u tell me what is this problem and how much will it cost to fix it completely.

[mani2263]

The dry and wet compression test is a standard test used to determine the condition of the pistons and rings, cylinder, valves and seats, and even the head gasket, and is carried out as follows:

1. Using an air line, blow away all dirt and debris from around the spark plugs.

2. Start the engine and allow it to warm up to operating temperature.

3. Remove all spark plugs and disable the high tension coil and the fuel pump.

4. Screw the compression tester into each cylinder in turn and crank the engine, making sure the throttle is kept fully open. Crank the engine for about four compression strokes and record the readings.

5. Check the readings. The lowest reading cylinder should not be less than 75% of the highest reading. Some manufacturers specify a minimum reading and any reading lower than that is unacceptable. You can check the vehicle service manual for these figures.

6. If all the readings are within specifications, there is no need to do the wet test but if there is variation between cylinders, then squirt about a tablespoon of lubricating oil into each cylinder and repeat the test. If the pressures increase appreciably and come up to the manufacturer's specifications, then you can be sure there is piston ring and/or cylinder and piston wear.

7. If after adding the oil, the pressure does not go up, your valves may not be seating properly and that could be for a variety of reasons. If there is no pressure rise in only one cylinder, it could be because of a blown head gasket.

Please take note that you never do a wet test with a compression ignition engine, i.e. diesel engine, because the additional oil may ignite on compression!

Best explanation

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[mani2263]

• So far I Only see Xulfiqar a professional with the widest & broadest spectrum of knowledge on vehicles & engines. over this forum

The way he shares the tiny bit of info about cars specially mercedes clearly shows his passion for cars and the mercedes star.

Honestly i wish i'd have met him before in real in Pakistan.

am just an amature with surface knowledge out of my appetite for motor vehicles and gadgets.

My salutes to Xulfiqar for his contribution to this forum., and his occassional wity comments

Dear please guide me some honest workshop. I recently bought city 2009. Due to trust didnt checked/got it checked in detail. But i am now out of choices. The meter is tempered. 2 major issues
1. Empty coolant reservoir after 350 to 400km drive.
2. Car with its windows and door close fills with smoke of passing by truck etc....

1 is the major issue. Wana some honest mechanic/engineer to trace the actual problem. Please guide in this regard. I visit Lahore every weekend and belong to lahore basically.

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[syed.siddique.rasool]

My 2000 model indus coroll car diesel engine cosmuption mobil oil shoul i start with compression test?

[usamah007]

Rustam bhai .. same problem here my cultus was hitting 140 in fifth gear easily without any lagging or misfire even with AC about a couple of months ago , but then i got my carburetor serviced there was some issue with butterfly in a nutshell the problem regarding with butterfly was resolved there was terrific pick .... But right now i notice in few days my car starts misfiring in 4th gear when it hits almost 100 nd same when i shift to 5th gear ... It misfires nd crazy jerks at 110 or 120 ... with AC on the problem is high nd with off AC the problem is still there but with lesser intensity ... So it is also a perk of retarded ignition timing ?

[rustam54]

Try to get access to a timing gun and share the timing. Its been long and I dont remember the factory values. An exhaust scanner and timing gun is your way to reach factory spec.

[RehanBhatti]

You can do it without a timing gun. Just advance it untill u hear engine knocking. Then back it off a bit. Try to hear engine knocking again under load like AC on. If no knocking then u r good to go.

[anon71378895]

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