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-   -   STARTING PROBLEMS "COMPRESSION ?" (https://www.scoobynet.com/general-technical-10/806347-starting-problems-compression.html)

J800BBT 22 December 2009 06:22 PM

STARTING PROBLEMS "COMPRESSION ?"
 
Tried starting my car this morning and when its turning over its sounds like theres no compression so as i took a step back and shat myself i decided to strip it down and have a look to see if the timing belt had snapped or possibly jumped a tooth anyway had a look belts fine and all the timing marks line up spot on bit worried now coz i havent got a clue because in theory it should start so does anyone have an idea ?????

J800BBT 22 December 2009 06:23 PM

ps its a 97 classic uk turbo

STI_Baly 22 December 2009 10:39 PM

Checked your spark plugs? and exactly why do you assume it has no compression?

scoobiewrx555 22 December 2009 10:56 PM

Could be crank position sensor or coolant temp sensor.

J800BBT 22 December 2009 11:43 PM


Originally Posted by STI_Baly (Post 9113867)
Checked your spark plugs? and exactly why do you assume it has no compression?

thats what it sounds like when turning it over as though it has no compression but checked the belt and timing marks and its all bang on would faulty plugs make it sound like that?

scoobiewrx555 23 December 2009 12:46 AM

If it's not even making any effort to fire at all then it could well be the coil pack. Generally speaking even if a plug was faulty it would still try to fire and perhaps run on only 3 cylinders and throw a cel. If you flooded the engine then it probably wouldn't fire at all until it had dried out but eventually it would fire.

For it to start fine the day before and run all day, then you switch it off and go back to it the next morning only to find it won't fire is unlikely to be a compression issue, more electrical or sensor.

It's more likely to be either coil pack, coolant temp or crank position sensor has gone down. Check those first before you start coming to other conclusions.

J800BBT 23 December 2009 06:45 AM

would that make it sound like it sound different when turning it over coz it does sound like its got a snapped belt but it hasnt coz ive checked that and the timing marks and its bang on i'll test the coil pack and make sure the spark plugs are working is there any way i can test the other sensors to rule them out ?

Brett_555_Sti 23 December 2009 07:21 AM

If you are worried about the compression, have you actually checked cylinder compression with a compression tester?

Remove a spark plug, put it back into the spark plug lead and earth the metal part of the plug, them get somebody to turn it over, you should have a nice blue spark. I would check for spark first.

Is the fuel pump running/priming, when you first switch the ignition on?

Check the crank pulley key aswell as they sometimes shear/wear out.

Turbotits 23 December 2009 07:28 AM

Sound like could be bore wash. When the car was very last started was it just for a very short while? maybe to move it on a drive or something?

Remove the plugs< disconect the crank sensor>to stop any stray spark and to stop anymore fuel being pumped in and give the car a good crank with no plugs in it> Give it a good 5 or 6 turns>

Clean and regap plugs or fit new ones>

connect crank sensor and try to start.

madscanman2 23 December 2009 11:59 PM


Originally Posted by Brett_555_Sti (Post 9114030)
If you are worried about the compression, have you actually checked cylinder compression with a compression tester?

Remove a spark plug, put it back into the spark plug lead and earth the metal part of the plug, them get somebody to turn it over, you should have a nice blue spark. I would check for spark first.

Is the fuel pump running/priming, when you first switch the ignition on?

Check the crank pulley key aswell as they sometimes shear/wear out.

when subaru main dealer mate done mine he removed all the plugs before testing it and got reading s as low as 98 psi on 1 and 2 , and 120 on 3 and 4 , after rebiuld , took it back kicked off and they got 150 psi on cyl one but rest of the plugs were in , they ended up putting over sized ones in and doing job right , he noticed there was some thing wrong as it started half a turn extra , before he done test. he has worked there 15 yrs know s his stuff , but not a clue on tunning , cheers probally no help to you s ,


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