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help please cars driving me crazyyy

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hi all this is my first post here so bare with me...

ive got a 2002 wrx impreza

brought it for £700 with head gasket gone and crank knocking.

took the engine out stripped it all down ,

sent the heads to get skimmed ,( i could see where gasket had givin up)
removed the crankshaft and sent away to get reground to 0.25

brought new mains and big ends full engine gasket set

no4 piston had started to melt slightly

brought a new piston and rod

re glazed the bores and everything felt and looked good

stripped oil pump and all looked good

built my engine back up fitted into car and whaeyeyeye

so after 500 miles of driving sensibly,  (no rpm over 4k and  graduated acceleration)I dropped the oil out and filled up with some new
I checked the oil that came out and it had no contaminants init. brilliant !!

so with 500 miles on the clock and new oil I thought id give it a little more acceleration than normal maybe 5k
and after 20 minuets of driving it started to over heat and started knocking !!!

so its sat on my drive waiting for a strip down...

 anyone have any ideas ?? pleaseee  


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hi welcome to the club.was your coolant level ok,my hatch use to overheat only if i accelerated at about 5k,all coolant use to just go into overflow and not round engine,new radiator caps and lot of time bleeding system cured the over heating.i never built a engine but could be worth checking.

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Hi n welcome, sorry to hear that it's knocking again bud [emoji19]

I've only ever built the 1 boxer lump but here's a few things that might be worth considering for the rebuild .

Most reputable builders advise not to regrind the cranks and only suggest re using a crank if it's mint or just needs a light polish .

I used plastigauge to double check the big end ,mains and cam caps clearances as it's cheap and only really costs a bit of time

did you allow for the skim when calculating the head gasket thickness?

Did you check the deck face /height ?

Even though the engine i rebuilt had nothing wrong with it ,I made sure the oil cooler (along with everything else ) was chucked through my engineers "hot wash" to make sure everything was über clean and bought a new oil pump/block bolts

But I did spend out on uprated internals Apr ,acl,cossie,Mahle, ect... so wanted to protect my investment a bit

Let us know what you find and hope it's not too serious

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Honestly I didn't check the deck height or allow for any head skimage , but have been changing head gaskets for 4 years now on more regular vehicles Renault Audi Peugeot Citroen etc.. And have never had a problem with that sort of thing, it did run perfect for 500 ish miles not knock or overheating , I'm hopefully taking it out over Christmas and will keep you posted , it didn't know wheather it's that I've not ran it in properly :(

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Yeah being ally the deck type , height and straightness makes a bigger difference on contact area against the underside of the head gasket.

My heads and deck face had a minor skim which didn't affect the comp but the deck height and difference in piston bowl did .

If it turns out to be bearing I'd definitely recommend the red plastigauge and a new crank if possible.

there's quite a few opinions on running in but here's what I did

10 w 40 Mineral oil for 250 mls keeping it off boost and under 3k and engine braking whenever possible.

Fresh mineral oil new filter still off boost and engine braking but up to 4.5 k till 500 mls

500 to 1k new oil n filter then gradually increased the off boost rev limit by 1k every 200 miles (700 miles 5.5k ect)

With occasional spurts of "actuated" boost (0.5 bar) under 4k but no higher boost for me untill mapping day ( as I was running a bigger turbo and different cams)

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  • 2 weeks later...

Well decided to take engine out yesterday and have partly stripped it to the point that the sumps off intakes off so looks like a bare complete engine ,anyway I've noticed small prices of copper in the sump so im thinking a big end bearing maybe , also I've noticed abit of play in the rear cylinder big end I did this by rotating the crank back and forth , so What's to cause this ? Oil pressure ? never had an oil pressure light on...

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Did you allow for the crank regrind and buy "oversized " shells and check the "end float" ?

did you use graphogen builders paste or just oil on the bearings when assembling ?

Did you insure the engine/crank oil galleries,breather system,oil cooler ,sump ect .... were clean n clear (been through the engineers hot wash and rodded through ideally).

Did you prime the oil system before initial start up by pulling the crank sensor to let it turn over but not fire ?

Over doing the instant gasket can lead to bits breaking off and blocking oil galleries and ports in the crank as well.

New crank /shells and plastigauge on assembly should rule out crank clearance tolerances

Best of luck n keep us posted fella

If it's not broke .....upgrade it

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