Pulsar low compression - Help plz!

gh4z

New Member
Hi, any help here would be a GOD SEND....

I have a pulsar gtir... obviously :)

It was working fine, then one day it started running like a bag of nails and sounding like a subaru :/ lol
Compression test showed cyl 4 was down on compression... 40 PSI...
So took the head off, had it skimmed, put a new HKS Gakset on her bolted her back up, and compression is the same...
infact... cyl 1,2,3 are up to 200 PSI now and 4 is still @ 40 PSI.

I have been saying it was the rings but my mate was set on the fact the head was warped... which apparently the company that pressure tested it said it was.

Any ideas guys?

The winner will get a big fat sloppy one :)

Thanks in advance and again any help would be greatly appreciated!
 

GTiR-Aholic

New Member
took the head off and had it "skimmed"... did they not do the valves, guides + seats?....

If they did.. then you got piston ring failure but if they didnt.. then you're back to square one.

You should do a leak down test on the pistons to check the rings - i always do this after removing the head with diesel/parafin.

More info on what you done with the head would help i.e. valves/guides?
 
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pulsarboby

Guest
cracked ringlands as above.
you really should have had a close look at that piston whilst head was off
 

kirko

Member
pour some oil down the plug hole then do a compression test if its back to normal its piston or rings,
if its the same then its valve related
 

gh4z

New Member
Well, just got in and there are already replies!
Fair play… I genuinely appreciate the quick response and help peeps

Well, the info is.. apparently the head was pressure tested, skimmed and the valves were sealed and fine?

To do the rings, can it be done from the bottom end or does that mean taking the head off? Rough guide? :p
A HKS gasket that was fitted when she was put back together.. am I right in thinking that the HKS gasket is knaffed now if we have to split the head off again? Or can it be re-used? As the car hasn’t been run yet… just compression test done? Its been torqued up for about 4/5 days now.

Once again guys, thanks again for the help!
 

PobodY

Moderators
Staff member
Don't you just give the MLS ones a few coats of hair spray and they're (almost) as good as new?
 

GTiR-Aholic

New Member
gasket will be fine to re-use and the bolts I'm sure they're not stretch bolts so it should be okay too but don't take my word on the bolts.. find out for sure.. someone else will come along and correct me soon enough I'm sure lol

You can test the piston rings without having to take the head off.. as advised in a previous post :)
 
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pulsarboby

Guest
yep as carl just said, head and sump off to get pistons out, but you may have to remove block aswell if its badly scored, so if i were you i would just drop the whole lump and pull it apart in comfort on the deck.

the bolts are stretch but can be reused 2-3 times so thats not a prob
also the same with h/g as above make sure the silicone hasnt broken down on the surface of it, if it has then remove all the silicone and give it half a dozen coats of hairspray and it will be fine.
 
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