Newbie advice needed for AUM re-build

Discussion in '1.8 & 1.8T' started by Marcus.w, Aug 20, 2016.

  1. Marcus.w New Member

    Joined:
    Aug 20, 2016
    Likes Received:
    0
    Location:
    Peterborough
    Hi I have a mk4 golf gti with engine code AUM, I would like to buy a second engine to re-build and upgrade in my spare time, as this will be my first time doing anything like this I'm thinking it might be best to get the same engine code so it will be straight forward to swap into my car. although I'm guessing that nothing is ever straight forward but at least I would not have so many worries with the electrics?

    I have spent ages online trying to find books or any information on how to go about this project in a professional way, I'm not getting very far with this.

    my aim is to end up with about 250bhp daily runner, I would like to have the internal components blueprinted, I'm very interested in trying for a dry sump set-up and perhaps water/meth injection, use of hybrid turbo,

    I'm a welder earning half decent money but the problem is I just don't know what parts I need to buy?
    I would like to get the best components and have the time to save for them, could anybody please give me a list of parts that I can use for this? also if anyone knows of a good book on this subject? I would very much appreciate any advice, Thanx
     
  2. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

    Joined:
    Jul 26, 2006
    Likes Received:
    3,320
    Location:
    Creating Pfredstarke
    I will answer later.
     
    Nightroamer likes this.
  3. fasteddie

    fasteddie Banned

    Joined:
    Oct 22, 2003
    Likes Received:
    672
    He is the man to write it up ^^^
     
  4. Marcus.w New Member

    Joined:
    Aug 20, 2016
    Likes Received:
    0
    Location:
    Peterborough
    ahh thanx very much, will check back later
     
  5. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

    Joined:
    Jul 26, 2006
    Likes Received:
    3,320
    Location:
    Creating Pfredstarke
    150-180 ps AUM/AUQ rebuild.

    In 2001 VW cost cut their cheaper sub 200 ps/9:5:1 compression 1.8T engines internally, using cracked rods with tapered small ends and pistons with smaller 19mm grudgeon pins.
    With the cost cutting done internally, the new engines benefited from VVT, LSU 4.2 lambda sensors and a new ME7.5 ECU with more memory.

    Transverse engines like this are the AUM, AUQ, ARY. Other engines such as the Ibiza AYP, Leon/Toledo/TT AJQ carry the beefier rods as the 210/225/240 20vTs but with 9:5:1 CR.
    The base heads are all the same, except a small hole on the cam cover end and exhaust shims on the 210-240ps engines.
    Some pre EOBD engines do not have VVT.


    Rebuilding these engines are as any other engine.
    My experience is, the choice of components used for assembly will determine the durability of the engine.

    Most bores/pistons tend to be within spec, meaning you can use standard size rings for reassembly.
    Most times the OE piston rings are well within spec, even after 140k miles. If you most change then, my preference is to use OE VW/Audi rings. These are double what they cost on ebay, but are specially coated unlike aftermarket parts by the same supplier.

    Ideally crack rods of the AUM and AUQ are one use and require a new set if they are disturbed. The bearings from an ARZ, AYP and AJQ are the conventional 20mm small end split type with a tab.

    Companies like Integrated Engineering do a 19 mm pin H section replacement rod that uses normal main bearings. These bearings are the same as the older EA827 engines such as a AEB, KR, 9A, ABF or PB engine.
    Bearings are usually pretty low wearing if the engine is treated well in particular the mains. Measure to confirm. If they need replacing then bearing shells by KS, ACL, seemed to have worked for me. Some others have used Glyco and King brands.

    20v engines are notorious for blocking the oil pick up. This happens when the plastic for the dip tune stick breaks up and falls into the sump. Do check and clean the oil pump strainer.
    If you do not know the history of the engine, I would replace the oil pump as well, unless you wish to transfer a known one. I have used 'Topran' parts as replacements.

    It would be advised to replace the water pump while you change the timing belt and auto tensioner. Aftermarket metal impeller W/Pumps are widely available.

    Check damper and flywheel crankshaft seals while to you at it and replace if required. Aftermarket parts of good quality are are fine. Rear seal comes as with the aluminium carrier as well.

    Inspect the PCV breather hoses while you are at it. They do perish, cause air leaks and poor running. I have seen lambda correction tend to clip at 25% adding fuel to maintain stoich when this occurs!

    Cylinder heads on 20v engines over 100k miles, do suffer from excessive exhaust valve guide wear. This inevitably leads to poor seating loads and exhaust head failure. Sometimes the evidence is left by wet exhaust valve stems when you look into the exhaust port of an engine that was recently running (obviously with the turbo assembly removed). Do get a trusted machine shop to check this and replace all 8 valves guides at least.

    VVT tensioners do fail as well. However you can transfer the known good one from your current engine, else you renew. OE parts from TPS or your dealer are the best bet, though more expensive.
    Make sure to change the metal gasket and half moon that is under the VVT tension valve. They tend to leak with mileage with oil potentially getting into the gearbox and clutch disc!

    With your engine built, you can look at squeezing more power out it no problem.
    The stock 5304/5303 turbo is pretty eager and a good remap does unlock more torque, response and power from the default hardware.
    You can fit a hybrid turbo that is similar to a 210/225 spec engine ( but in the same package) and run more power with mapping.

    I have left out steps such as adding oil and so on as I expect you do not need to know how to suck eggs...I hate it when folk do that with me!

    That is the basics I have observed over some time.

    Any questions just ask.
     
    Last edited: Aug 21, 2016
    Nightroamer and fasteddie like this.
  6. Marcus.w New Member

    Joined:
    Aug 20, 2016
    Likes Received:
    0
    Location:
    Peterborough
    Thank you for the great reply Toyotec, I think I may have been over complicating my plans due to reading so many different things on the net, when I bought the car in January this year it had 113k on the clock, so I immediately had a new cambelt and water pump/auto tensioner fitted, the pump has a plastic impeller but I have read that this may be a safer thing than a metal one because if the unit fails it is less prone to jamming? I have orderd a new Forge diverter valve and TIP also have installed NGK spark plugs and new OE coils, I will be putting on a solid bar strut brace at the front next week.

    I will go for the H section rods and OE rings just to be safe, when I get the second engine and have stripped it down/de-greased I am thinking of sending the case to a machine shop for align boring of the crank shaft caps , having the deck skimmed and the cylinders honed, the crank ground and balanced I am wondering if after the deck skim will this effect how thick the head gasket will need to be? how do I measure and calculate the stroke length? would hate to smash pistons or end up running a bad compression ratio. after the align boring I am thinking that the machine shop will tell me the I/D of the bearing caps and I will use this measurement when ordering the new bearings?

    do I need to get the case heat treated to give me a more uniform grain structure and added strength?
    Is there an issue when fitting the crank oil seal at the flywheel end, I think I read that there is a crank position sensor that only vw technicians can fit?

    moving onto the head, shuld I get Inconel valve seats?
    would it be best to get Bronze valve guides? I think these offer reduced friction?
    is it worth having the combustion chambers and valves ceramic coated to help reduce detonation? or can I just mirror polish for the same effect.

    I have some skills using die grinders and am thinking of opening out the intake runners with a carbide cutting tool but I'm thinking its best not to mirror polish in this area as it may be detrimental to fuel atomization? I will port match the manifold to the head on both inlet and outlet sides, is it ok to mirror polish the inside of the exhaust runners?

    thanks for your help so far mate, I hope Iv not gone on for too long or chatted a load of rubbish, by the way how do I thank for a useful post? I cant see a thank button. no worries if it takes time for a reply, I'm in no hurry.
     
  7. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

    Joined:
    Jul 26, 2006
    Likes Received:
    3,320
    Location:
    Creating Pfredstarke
    No the plastic ones are the ones prone to failure. I am not really up to speed with what the internet says to be fair, nor do I bother.

    As I said honing on a block is not required if you measure and it is within tolerance. Neither is align boring as you are not required to replace the main caps.
    Crank regrinds are usually when you damage the crank journals and require resizing to the next undersize.
    Non of the above is required for a rebuild without justification.

    Heat treatment not required. Crank oil seal is a job most DIYers can replace.

    Not required mate. Not for a general rebuild.
     
  8. Marcus.w New Member

    Joined:
    Aug 20, 2016
    Likes Received:
    0
    Location:
    Peterborough
    ahh thanx very much for the info, I will get the metal water pump for the new build,

    you have saved me a fair amount of money with your advice, looks like I would have gone way over the top if I had not asked about this.

    I'm moving to a new house with a garage at the end of the month, cant wait to get started with this project,

    I will try my best to take pictures and write a bit about how I get on.
    thanks once agai, all the best mate.
     
  9. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

    Joined:
    Jul 26, 2006
    Likes Received:
    3,320
    Location:
    Creating Pfredstarke
    No problem whatsoever!
    Feel free to share.
     
    Paul A Towers and Nightroamer like this.
  10. Paul A Towers New Member

    Joined:
    Mar 8, 2019
    Likes Received:
    0
    Hi Toyotec,

    Great bit of info above, saved me searching through the internet, as I am doing a similar project.

    Just one question if you ca help me, I have a full AUM engine ready for strip down, that includes all ancillaries except turbo. My car currently has the AUG engine.
    I want to refurbish ALL of the AUM including the head. What else would I need to change over to get it all to fit.

    I know the throttle body is different, mine being cable. Does that mean I would need an AUM pedal box?

    Thanks in advance [:D]
    Paul
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice