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General => The garage => Topic started by: leeroy20vt on 16 October 2009, 14:26
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as above what should the compression be in psi
thanks
lee
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any one i have searched :cry:
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Not sure what the actual value is but generally if all 4 cylinders have a similar amount of pressure and hold it. I think that is how you are meant to test it??
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90-100 springs to mind but dont know where from though.
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90-100 means it may just about run but it's really quite f**ked.
i would want to 180+ across the board a healthy abf crancking at a decent speed should be around 200 psi mark
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cheers guys dunno if it matters its a 9a engine not a abf
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9A is a tad lower tho dosent really make any differance TBH compression gadges ain't exactly accurate animals i have a few and they all read a bit diffrent. but some rough values
< 100 = BROKEN proably terminal
100 - 125 = scrap/ it needed a rebuild some time ago
125 - 150 = would like a rebuild
150 - 165 = bit worn but it'll
165 - 180 = ok bit low but choudl be gadge readin low or starter spinning slowly
180 - 200 = it's gonna go some
200 + = race engine is it
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so when u say below 100 terminal what are we looking at u reckon
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if your lucky it'll be valves ether bent or the guides and seats so worn there not landing on the seats square. more than lilely the pistons are damaged ( rings exposed or very worn it need a rebore and new pistons prob straight to 2nd os
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if your lucky it'll be valves ether bent or the guides and seats so worn there not landing on the seats square. more than lilely the pistons are damaged ( rings exposed or very worn it need a rebore and new pistons prob straight to 2nd os
cheers danny hopefully will find out tues as im taking engine back out and stripping it
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persoanly i woudl be tempted to shove so oil down the plug holes anddo another compression test, the bigger the differance between wet and dry test the more knackerd the rings are.
the other trick is make an airline attachment to screw int he plug hole then you can pressurise cylinders and hear/ feel it gettign past teh valves or comeign out the sump breather
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good idea m8 im goin to take it out tho got a leaky crank shaft seal to
i cant see it being to nackered as it goes really well other than the smoke :embarassed:
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if it starts you get it to start it'll rebuild but is it economical to rebuild it. the only way to tell that is to pull the cyl head and sump off.
get the pistons out and masure up teh bores if there ok have a good look at the pistons if they look servivable, carefully get your nails in the gap of one of the compression rings if you can spread it a fair way before it snaps they were knackerd. if not it wasent knackerd.
may be a good hone and a set of rings if your lucky. but if it needs a rebore the cost of oversize pistons dosent make the block economicaly viable normaly
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if it starts you get it to start it'll rebuild but is it economical to rebuild it. the only way to tell that is to pull the cyl head and sump off.
get the pistons out and masure up teh bores if there ok have a good look at the pistons if they look servivable, carefully get your nails in the gap of one of the compression rings if you can spread it a fair way before it snaps they were knackerd. if not it wasent knackerd.
may be a good hone and a set of rings if your lucky. but if it needs a rebore the cost of oversize pistons dosent make the block economicaly viable normaly
it starts and runs really well part from the chuffs of smoke out the rear and the very low compression all below 100
well this is my findings of today
(http://i131.photobucket.com/albums/p319/leeroy8v/ABCD0005-6.jpg)
(http://i131.photobucket.com/albums/p319/leeroy8v/ABCD0006-6.jpg)
(http://i131.photobucket.com/albums/p319/leeroy8v/ABCD0007-5.jpg)
(http://i131.photobucket.com/albums/p319/leeroy8v/ABCD0008-5.jpg)
looking at the bores they havehoning marks on them still looking at the the valves the very coked up
theres a little play in the pistons from side to side
goin toto take pistons out tom and see if the rings look ok ive left them full of brake fluid over night to see if its gone by the morning
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it's running very cold and oily to that, 1&2 espectaly
it's going to be worth poping the tappets out and relieseing a few of the valve springs and giveing the vlaves a rock just to see if there is play there but i expect you'll find there ok
has your enigne ever been layed up for a long time ? cos i think you may find the rings have stuck, if an enigne layed up long time all the oil can drain down allowing moisture to reach the rings ( takes a long time or really sh!tty storage ) and they rust slightly causeingthem to go tight in the pistons and stop them moveing about, ether that or it's been rebuilt buy a numptie who's lined up the gaps in the rings
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cheers dannyp
yes m8 has been stood for a while got pistons out today all looked ok part from a liitle score mark on side of 2 pistons.
i took it up to the engineering place were i manage to get some rings from £127 :sick: he took old ring off placed in bore and said theres a big cap i couldnt see it but there u go lol
so he is rehoning it as bores glazed so he said and puting rings on pistons for me and giving them a good clean the little holes behind oil ring are blocked to should have that back tommorow
also having head skimmed and i will put new oil seals in check for play and reseat the valves so in total today the engine has cost me £240 which didnt think was to bad ?? that includes all work and head gasket set and bolts
when u say running very cold what would cause this m8 thinking about it the temp gauge only goes up to a quarter then fan cuts in
cheers for the info
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still not an expensive engine really and it'll have nice new rings to abuse :smiley: just don't be to nice when running it in, not revving it silly but make it work abit
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how many miles to run init in do u reckon i need to get it set up again on the rollers but dont want to take it there straight away
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yes it will need setting up again, as the compression will have increased but without the oil seepage the mixture will be less prone to detonation so it chould be anywhere.
as for running it i can't give you the answer and someone will disagree, my personal oppinon is they don't need meany miles at all if you build it righ so i often use the hard and fast approach to breack them in. ( unless it's a really old engine desing ) . as soon as it's running i think it should be driven, don't make it labour but keep the revs off for a bit, once it's warmed and done a few part throttel pulls to 3000 rpm i'll be giveing it full throttel between 2 & 3 k rpm then 2& 4 k rpm, then 2&5 k rpm. and letting it engine brake back down in between.
if you build the bottom end to tight that method can and will spin a shell, but as all the parts are produced to tight tolerances and it's possibel to measure them quite easly there should be no tight bearings so see no reason not to give them some load. tho i would leave the last 1500 - 2000 rpm allone till its done a few hundred miles
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thanks again m8
well made some good progress today got lump back yesterday afternoon but had bits to do so made a start a today
got pistons in bottom of con rods all tightened up according to auto data so bottom end all back together
got all vavles reseated but they sent wrong gasket set so couldnt get oil seals in and head back together
fingers crossed she will be good this time :angry:
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soz just noticed a mistype, ment to say i can't give you the answerer in regards to how to run it in just my opinion. it's your motor your choice but thats my opinion on how to do it
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soz just noticed a mistype, ment to say i can't give you the answerer in regards to how to run it in just my opinion. it's your motor your choice but thats my opinion on how to do it
i got the gist of what u was saying m8 lol
well 90% back together and it runs bit tappy but then i sopose it to be exspected i think i will just drive it sensibly for a few miles and slowy build it up
again thanks for ur help danny p