Golf Mk4 "APK" engine conversion

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Golf Mk4 "APK" engine conversion

Post by silverbullet »

There's a little collective group of us looking at using the so-called "Gen V" inline crossflow engines as a successor to the AGG, as supplies dry up.
It will be a 50degree installation using JX mounting hardware to make life easy.
(I have a vested interest in making certain key parts for the conversion, such as a properly designed cast alloy sump and an oil pickup adaptor, for starters)
So I bought an absolute shed of a 1999 Gti with just 90k on the clock and still in MOT, drove it home without incident other than diagnosing a stuck-open thermostat.
It's quiet, torquey and goes well when given the berries but the car itself is utterly used up. A well-used 20 year-old "soft-touch" interior is not a pretty sight...
Its the APK engine with cable throttle and this one has aircon which suits my bus to a tee :)Image

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Re: Golf Mk4 "APK" engine conversion

Post by pkrboo »

Had one of these engines in a 2001 golf I owned in USA, bought it with 103k sold it 3 years later with 155k on it and 3 years later it was still going strong with over 200k on the clock.

Not a well liked engine for some reason by some, but I think they are great.

Will be interesting to see it in a conversion. Lots of new beetles had them too.

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Re: Golf Mk4 "APK" engine conversion

Post by pkrboo »

Oh and make sure you fit a water pump with a metal. Impeller as the plastic impellers break easily.

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

pkrboo wrote:Oh and make sure you fit a water pump with a metal. Impeller as the plastic impellers break easily.

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Thanks for the tip!

90k over 20 years suggests light usage (or too many short journeys?) only had one black "puff" out the exhaust when I nailed it but I think that the the stat is stuck open so its been running rich for a while.

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Re: Golf Mk4

Post by Cobra88 »

I would be interested if the kit is not silly money

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

The idea is to make what's not available (sump) and identify which proprietary bits actually clear everything and work e.g. epytec, jx, adapted or custom mounts for each side, most appropriate clutch/flywheel and finally exhaust and wiring harness.
There could be an option to use the Mk4 dash (immobilizer is part of this afaik), stalks and MFA functionality but that's not my dept.

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

I've got the plastic dross out of the way for a start.Image

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

Now, it turns out that these engines have a reputation for oil consumption, even the handbook states that 500ml/1000km is considered normal. I can't comment because I have only driven it for 90 mins at 50mph.
Hmm. A bit of online research reveals that some engines are fine, others not so fine. Sensitivity to initial running in conditions and oil spec are a factor, along with tales of a piston ring manufacturing fault (specifically ring #2, allegedly being marked "top" on the wrong side...) causing the crankcase to pressurize due to ring blow-by and so use oil when under load.
There's a lot of it published online.
Annual cleaning of the crankcase breather to remove condensate "mayonnaise" would also seem to be of benefit.
I'm not going to fit a 90k engine that is supposed to suffer these failings without investigating further!
Thankfully, an inline 4 with no distributor or auxilliary shaft is a pretty easy thing to sort out, parts required for a quickie rebuild after a bore hone/glaze-bust: head gasket set, head bolts (?), ring set, big end bolts, crank bearing set.
My Mk4 book o' lies arrived today so I'll have the engine and box out tomorrow, hopefully the dash and wiring too.
I want this heap gone asap.

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Re: Golf Mk4

Post by Aidan »

probably depends where it was built and the parts stream into each plant, there are I believe 3 German engine plants and one in Poland for VW plus the Audi plant and plants in Brazil and China; my local VW parts guys know a little about the dodgy ones, like the Mk5 1.6 engine that throws rods, built in Brazil, as they keep coming up with repeat orders for parts or in that case engines :roll:

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

Last mot emissions looks ok to me, nice and clean. Recent annual mileage is paltry.
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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

Just realized that I hadn't checked the handbook for any service record. I may have struck gold...
Full main dealer stamps for first 7 years and almost exactly the same annual mileage of ~10k, taking it to 73k by 2007.
So its done 17k in the last 13 years :)

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

Spent most of today taking Golf apart. Taking the dash out. Ugh. What a job! Brittle plastic and hidden fixings. I would not want to work on modern cars every day...anyway the engine is out and on the deck.
Downpipe nuts refused to budge, even though the cat looks recent (the muff coupling on the exhaust released easily) so I dragged it out with half the exhaust still attached and I'll powerfile the nuts off tomorrow after I have extracted the loom...
This engine also has just one lambda sensor fitted to the exhaust manifold (later ones have two, pre- and post-cat) which keeps things simple.
PAS uses green oil but I dont know if the pump will be happy with ATF after a flush out?ImageImageImage

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

Engine wiring harness is easy. Hours and hours used up taking out the fascia, heater, dash support beam, steering column.... just to extract the massive body harness (encased in random bits of plastic trunking) which is needed just for the immobilizer wiring.
But its now done. It's about half a mailsack full! Now all I need is space to lay it all out and start unpicking it...

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Re: Golf Mk4 "APK" engine conversion

Post by silverbullet »

If the wiring schematics are to be believed, the engine management is effectively stand-alone but the immobilizer is part of the instrument pack (2nd generation) and since I dont fancy the modern blue dials look (even if the trip computer is a nice feature) it seems that an immo delete is possible.
I have kept the adjustable column and switches, just in case.ImageImage

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Re: Golf Mk4 "APK" engine conversion

Post by pkrboo »

Yes the immo is part of the cluster. I think it will be immo2, so easily deleted by someone with the right tools.

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