205 Low Compression on Cylinder 1

N

neilc

Member
VIP Paid Subscriber
Fellow Frogger
Joined
Jul 28, 2014
Messages
247
Location
Sunshine Coast
After putting rings and bearings in my Gti I ran for the first time at a sprint meeting. While the car went ok it was blowing smoke under acceleration down the main straight which I put down to an overfilled sump.

On return home checked compression cylinders 2,3 and 4 - 240 psi cylinder 1 - 80 psi
I am using a competitive .027” head gasket

I have since removed head couldn’t see any visible signs of damage on head gasket or head. Inverted head and poured petrol into combustion chamber of cylinder 1 the valves seemed to be seating properly as no petrol leaked out

What would be the liner protrusion expected with seal installed, I know it is normally measured with seal removed but I dot want to disturb liner if I don’t need to.

Where to from here is it possible to remove piston without taking engine out?


Any suggestions welcome
 
My guess would be a broken ring !But its just a educated guess. Test it !
jaahn
 
You can get the sump off with the motor still in ? If so, just drop the cap of No1 and push it up through :)
 
In days I long gone when engines needed more work than today I several times took a long stroke piston out through the sump, but not on a 205.

It depends on getting it past the rotated crankshaft, and whether you can get a piston plus ring compressor in that space to put it back. It's worth asking around to see if it's possible. Otherwise it's both head and sump off.
 
Head's off, so it's full steam ahead!
 
Easy job. Head off, sump off, undo rod bolts and withdraw piston/liner assembly out the top.
 
Make up a liner clamp to keep things in place :)
 
neilc said:
Peter would you know what the protrusion should be with seals in?
Click to expand...
Once you've removed the piston/liner, remove the piston and the seal, put the liner back in and then measure.
 
Or leave liner in place, place a clamping contraption on top and see what's what. You don't need much force to push the seal down until the liner touches the base and that will give you the protrusion.
 
The reason for the low compression no damage to the bore evident
 

Attachments

  • 36D79725-0E5D-4099-8B5C-A85FA097BCA8.jpeg
    36D79725-0E5D-4099-8B5C-A85FA097BCA8.jpeg
    542.5 KB · Views: 49
  • 3EB22443-B5D5-4650-B08F-A5190975A29B.jpeg
    3EB22443-B5D5-4650-B08F-A5190975A29B.jpeg
    599.2 KB · Views: 52
Ouch, what were the ring gaps on installation? Any bad detonation?
 
Running 98 normally aspirated.
Don’t know about ring gap perhaps someone on the forum can comment
 
In the first post you said you did rings and bearings. Are you saying you didn't measure the ring gap against the bore before installation?
 
Hmm we are just offering suggestions for causes from our computer keyboard.
Does the bore have any lip at the top. What is the wear taper in the bore.
Was the injector putting in sufficient fuel.
That piston does not look like it siezed or was very worn.
 
You must log in or register to reply here.
Top