Bad Compression

[newboost]

been having some problems with the car now for a little while now, have replaced and cleaned almost everything that was possible. Decided to to a compression test to see if there might be a answer to what was going on.

#1 130 psi

#2 130 psi

#3 130 psi

#4 130 psi

#5 70 psi

#6 130 psi

this seems to be not a good sign. i guess that it is time to pull apart the motor and rebuild it. What would some costs be for something like this.

I don't want to go all out just to make a good reliable motor. if any one can point me in the right direction that would be of great help.

[NA_Goodness]

Low compression could just be a melted valve, so only the head needs doing which lowers the price a lot. You won't know for sure until you pull it off though.

[Johnny]

sorry to hear bout the motor, hope you get it sorted asap so u can be out on the road again.

im sure theres plenty of threads on engine rebuilds, alot of shops offer rebuild kits with pistons, rods and gaskets so it makes the job easier. Are you going to be doing the rebuild yourself? or a mechanic shop?

choosing the right mechanic shop is crucial, its something you dont wanna skimp on, even if you have to save a little longer for it - being able to pull the motor out urself is an advantage as it saves on labour costs but personally if it was me, some tuners on this site build the motor and give you that "first-start" warranty as its in their care.

how much power are u going for and do u drive it on the track or jst the occasional spirited drive and squirt at the lights?

[BADR33]

one way to test if its rings is to drop a small amount of oil(10-20mls) in the cylinder, if compression gos up then its rings. if stays the same its something else.

[newboost]

the car was on it's way to the track.

had just put a hyflowed turbo,splitfires,boost controller, fmic, bosch 040 fuel pump and was ready to do the computer next, all these parts have all been on the car for about 3 weeks. boost was running at 9 psi until it was ready for a tune. guess i will have to look at rebulid before the computer now.

[JET-25L]

Yeah there's been heaps of rebuild threads done so far.. The cheapest and fastest option for you might even be to find a good condition and running motor and drop that in and keep yours for parts etc. Rb25 long motors are only about $800-$900ish now which is a couple days work to change over although if you're not after big power it might be the best solution. Really depends what your future goals for the car are. Could even put the second hand motor in and get the car going again but also be able to rebuild the blown one over a period of time.

You could easily spend a fortune rebuilding yours with all good quality parts and by a good workshop however if you're not quite sure of what you want to do with the car in future and you can't afford to have it off the road for a few months then that extra money you would have spent on the rebuild you could have spent getting the computer and the second hand motor and slapping it all together with your good parts already and off you go again. You always have the chance of being in the same position you're in now in a few months though with the new engine but there's no way to know that.

[trel]

sorry to whore thread, but my motor is screwed too....

harmonic balancer has worked its way loose over time... destroyed keyway on crank. no point in changing crank, may as well put new motor in mine too...

[STATUS]

  newboost said:

the car was on it's way to the track.

had just put a hyflowed turbo,splitfires,boost controller, fmic, bosch 040 fuel pump and was ready to do the computer next, all these parts have all been on the car for about 3 weeks. boost was running at 9 psi until it was ready for a tune. guess i will have to look at rebulid before the computer now.

its amazing how quick running this gear without an appropriate ecu can do damage.

[STATUS]

  trel said:

sorry to whore thread, but my motor is screwed too....

harmonic balancer has worked its way loose over time... destroyed keyway on crank. no point in changing crank, may as well put new motor in mine too...

there are a few ways to fix this cheaply if you cant afford an engine. Some impressive epoxies nowadays.

I had to fix a rb25 for a customer who forgot to tighten his properly aafter doing his own cambelt, done 4 trackdays and 20000kms since repair.

the product is a loctite epoxy, i will look up the number. Then use loctite shaft fit on the nose and balancer for extra security.

Edited November 15, 2009 by URAS

[trel]

trent, that all depends on the extent of the damage i assume though? i mean it's gotten to the point now where i can hear the tapping coming from the lower timing cover... give it some revs and it sounds like a whining/tapping sound as the revs increase.

any point in buying a new balancer and keys if i was to loctite everything?

by the way is this stuff almost like a putty? fills in the gaps where the crank snout has been ground down?