No Compression?

[mick.wheelz]

Hi all,

Went to fire up the 5SGTE last night and this happened;

http://www.youtube.com/watch?v=CR8gSvIESIU

It seems like it has no compression, but the cam timing is set right (from what i can see)

The bottom end has new rings, etc.

any ideas?

[thechuckster]

how did you setup the crank/cam timing?

marks on the belt are as good as the pleb that put them there - long rod down #1 spark plug hole, rotate until stops rising, then check both cams with all lobes for #1 pointing down and outwards (TSRM has more details on what marks to look for).

[mick.wheelz]

how did you setup the crank/cam timing?

marks on the belt are as good as the pleb that put them there - long rod down #1 spark plug hole, rotate until stops rising, then check both cams with all lobes for #1 pointing down and outwards (TSRM has more details on what marks to look for).

yeah i did the timing that way, making sure 1 was rocking on tdc with a long screw driver only issue was i didnt have a 3sg manual, i have one now so ill will check again

[CELICASUPRA7M]

180 out?
ten char

[mick.wheelz]

well, turns out its out because the stroke is longer.

its a 3SG head on a 5S block... following 3SG timing is pointless, will have to time it by getting the lobes aligned to where they need to be on the lifters

[thechuckster]

well, turns out its out because the stroke is longer.

its a 3SG head on a 5S block... following 3SG timing is pointless, will have to time it by getting the lobes aligned to where they need to be on the lifters

you have to setup the cam positions to suit the head and cams - which in your case is the 3SG heads. The 3SGE timing is essential for your head.

you may have discovered that the taller block is doing funky things to the belt - most likely the teeth in the wrong spot and forcing the cams to sit in the wrong spot when motor is at #1 TDC. See previous comments about not relying on marks on the block/belt.

Get the relevant engine manual from here: http://gt4.mwp.id.au/

Put piston at #1 TDC (and see if mark on crank pulley/harmonic balancer lines up with mark on the timing cover)

Cams should be in this position (note the notch in the #1 cam bearing/front seal for both cams lines up with a notch machined into the cam). This is from a gen #2 head/cam:

(larger version)

Line up the cam pulleys as per the manual (see two attachments - they're from the ST205 manual on MWP's site). You may have to use one of the alternate pin positions if you have issues with the belt.

Fuck around getting belt on correctly and under tension - again, pin position may vary from the manual to get the belt under tension and the cams in the right spot (due to the increased deck height of the 5S block). Then rotate by hand a few times and then re-check that your crank is at #1 TDC and the cams are also correct.

[MWP]

5S block is the same height as the 3S.
Need to use a 5S belt as the 5S oil pump has one less tooth.
As chuckster said, crank at TDC, cam wheels lined up with corresponding marks on the head, put on the timing belt, tension it up. All done.

[mick.wheelz]

5S block is the same height as the 3S.
Need to use a 5S belt as the 5S oil pump has one less tooth.
As chuckster said, crank at TDC, cam wheels lined up with corresponding marks on the head, put on the timing belt, tension it up. All done.

How can i possibly use a 5SFE belt, 5SFE head only has one cam gear... 3SGE head has two, there is no way it will ever fit.

Besides that fact, the 3SGE timing belt in use works perfectly, does not slip and is tight.

Every single time i have set the timing (which is 3 or 4 times) now it has been timed to the marks on the 3SG head, piston at TDC, etc.

I never use the marks on the block, nor on the belt to do timing. I set the No. 1 to TDC by hand cranking with a screw driver down No.1 to get it to its maximum height.

Then use the cam timing marks to align the camshafts.

I have set the timing on 3SGTE's and that 5S (with its orig. head) in the same way, and its always worked.

Part of my reason for thinking this, is correct me if i am wrong, but at TDC, the inlet valves should be just about to open, and exhaust should have just closed.

Therefore the cam lobes should be just touching the values (in opposing positions), when the timing is set by the marks the cam lobes are maybe 4-5mm off the position in which they would need to be to start actuating the valve...

Anyway, this is a non-interference engine so there is no harm in trying this theory out.

[MWP]

Hah, yes, my obvious ooops about the 5S belt... i meant the ST205 belt that has one less tooth.

[thechuckster]

sorry - thought the deck height changed when you went 5S. I figured the belt would be different assuming you started out with ST185 as the core engine.

The pic in my post shows both cams at #1 TDC. At this position, the engine is just about to fire, so both lobes will be around 90 degrees away from opening (e.g. intake closed as the pistons started the compression stroke, exhaust won't open until the motor has traveled downwards and is at the bottom of the cylinder.

edit: your assumption of 'the inlet valves should be just about to open, and exhaust should have just closed' describes the end of a 4-stroke cycle - or 360 degrees ATDC - where as #1 TDC is the end of the compression phase and ignition-timing-wise would be 0 degrees BTDC.

[frostyadonis]

is the 5s block fitted with the 3s timing gear on the crankshaft end?

[pandaah]

have you tried doing a leakdown test?... but yeh sounds like your valve timing must be completely in the wrong spot or bent..

[mick.wheelz]

FML, valves are all bent (bar two) on the intake side.

*sigh* so much for being a non-interference motor... I realize why it happened though, the divets in the pistons are designed to accommodate a valve on ~20deg angle, where as the G head is ~40deg.

This still does not explain why the timing was wrong initially, as it was set when the motor was out of the car and triple checked... i guess its possible the belt slipped/something else went wrong.

anyway, thanks guys for your input.

[trdee]

fark, sorry to hear man

[mick.wheelz]

fark, sorry to hear man

the ammout of dramas i have had with this bucket, it is turning into the failcelica... I am sure you can relate