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Thread: 4age head gasket - lend me your thoughts

  1. #1
    Forum Member 1st year Apprentice
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    Default 4age head gasket - lend me your thoughts

    Ok, well a few weeks ago my daily overheated (4AGE smallport engine). Changed the coolant, went for a short drive did it again, so figured it was either the head gasket or a water pump. No coolant in the oil/vice versa however.

    Anyhow, so I decided to pull the whole head off and do h/g, water pump, thermostat and gaskets. The head had supposedly been replaced 12 months ago by previous owner, so seems strange would do a h/g so soon.

    I've had a bit of a bad oil leak for a while around that area, I suspected it was actually coming from the head. Changed crank and cam seals a month or so back to eliminate those, but was still leaking. Has been burning about 1L of oil a week, so could be related.. I do a lot of km (around 700km a week ), but that's obviously a lot for a 220,000km engine.

    This is the view after straight after I pulled off the head today. Seems like obvious problems around cylinder 1 to me. I am pretty sure I pulled off the head pretty much directly up and straight off. Is the oil pooling there:

    1/ a result of oil dripping from the head as I pulled it off

    2/ OR an obvious leak in the head around cylinder 1?? Gasket appears to be intact.




    Head bolts didn't seem that tight to me when undoing, except for bolt 9 which was torqued down like a motherfucker. Although this was only via feel. I suspect the previous person did a dodgy job and didn't torque down the head bolts properly or in the wrong order. Head and block seem nearly dead flat though when testing with a straight edge thankfully, so shouldn't need machining.

    Rings on piston 1 or headgasket? What do you guys think?

    I'm going to slap it together with a new head gasket, but if it's all going to be a waste of time maybe it will be easier slapping another engine in there (if I can find one, seems to be becoming harder?)

  2. #2
    dont work in my backyard Domestic Engineer pandaah's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    looks like cylinder 4 has been burning more oil than any of the other cylinders... note the excessive carbon build up compared to the tops of the other pistons...

    i think the oil around cylinder 1 is just oil in the head when you took the head off... as it looks obvious to me you didnt drain the oil or coolant before taking the head off.. but i could be wrong

    my thoughts - if cylinder 1 was burning that much oil, and if you think thats where it was leaking from, it would of be blaintainly obvious when you did the cam and crank seals

    im thinkin head gasket is fine, i think its a combination of worn bores and rings, and / or stem seals in the head, but since youve got the head off, recon the valves, but pay perticular attention to the valves on cylinder 4, as youll see excessive carbon on the heads and around the base of the stem if the stem seals have been badly leaking



    yet i could be wrong...

  3. #3
    Olde mechanic Carport Converter oldeskewltoy's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    the oil comes up to the head from the oblong port in lower left of 1st photo, it looks damaged, the rubber(orange seal is misformed)


    Concerning cooling... it appears that cyl 2 and 3 may have had something to do with the overheat(they appear cleaner then 1 and 4)



    Here are the tighenting/loosening procedures for the head bolts... I'm GUESSING, but if some were barely tight... then the clamping force may not have been sufficient to hold the coolant while under pressure for very long.

    OH... one more thing... from personel expereince... DON'T forget the washers under the head bolts!
    Information is POWER... learn the facts!!

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    Your mum is a Conversion King TERRA Operative's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    A good trick when using genuine valve stem seals, is to use exhaust seals on the intake side (so all the valves have exhaust seals). The seals are exactly the same, except the exhaust ones are made of high temp viton, instead of the cheaper rubber.

    Just means the intake seals will last longer etc.

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    Jack of all trades Automotive Encyclopaedia mattysshop's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    From my experience all the 4ag's i've pulled apart and reassembled i have never ever had to use a new head bolt.. (despite them being TTY) they always loosened and tighened like banshee...

    4EFTE - HG popped within a few weeks.. so off came the head, i could undo the head bolts with one hand on my 3/8 extension..., new bolts (about $5 each), gasket, checked for straightness... all bolted up fine and run plenty of boost to test


    check or just have it surfaced to be on the safe side... new gasket, and for the sake of about $50... chuck some new bolts in there.. i may have just been lucky with my 4ag's not having ever to need new bolts, but mine never undone like your explaining? perhaps they didn't do the 90 turns on them once at torque.. if i was reusing bolts, i would tighten to the book (XXnm + 90 + 90) i would do the first 90, then a 45.. as they would have already stretched..

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    Jack of all trades Automotive Encyclopaedia mattysshop's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    there is a nice score in #2 bore... and they look glazed (picture with good Macro would help ) could be the oil burning...

    looks like a nice rack you have there

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    Spirited Backyard Mechanic Casey-G's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    Quote Originally Posted by TERRA Operative View Post
    A good trick when using genuine valve stem seals, is to use exhaust seals on the intake side (so all the valves have exhaust seals). The seals are exactly the same, except the exhaust ones are made of high temp viton, instead of the cheaper rubber.

    Just means the intake seals will last longer etc.

    hey terra, how do you tell them apart? i got a VRS kit for my 16v head and all the stem seals came in one package...??


    is it just a genuine part thing?

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    Olde mechanic Carport Converter oldeskewltoy's Avatar
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    Default Re: 4age head gasket - lend me your thoughts



    90913-02077 for the exhaust, and 90913-02090 for the intake.
    Last edited by oldeskewltoy; 12-01-2010 at 02:43 AM.
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  9. #9
    Spirited Backyard Mechanic Casey-G's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    obviously just a genuine part thing, mine all came together (not genuine) i wonder how they will hold up...

  10. #10
    Your mum is a Conversion King TERRA Operative's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    Yep, a genuine thing. I don't know what the aftermarket ones are made of though (I have aftermarket ones in my car at the moment, they'll be swapped to Toyota ones with the new head), so I can't be much help there.

  11. #11
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    Default Re: 4age head gasket - lend me your thoughts

    Thanks.. some useful things to think about. I flipped the head over and took some photos, and says a lot there. Cylinder 1 and 4 are wet with oil, and that surely would seem to indicate the rings are shot? Cyl 2&3 look the more normal ones to me.

    oldeskewltoy: I think you are right there about that deformed part of the gasket. Having a closer look, the viton part of the gasket was pierced, and that is where the oil may have been leaking from (not the full amount - think that was just when I pulled the head off).

    Oh guess what, no washers under the head bolts!. None at all! I had a look, but I am pretty sure there were none that have fallen off anywhere. Would explain the inconsistent torque across the head. Will get new bolts + washers to reassemble.

    Will try and get some close up of the bores soon. There is nothing noticeable with a finger nail over it at least. After cleaning up the head a little, there is some visible pitting in the quench areas of the head as well

    Time for everybody to cringe .. I've decided I'm going to get the head lightly skimmed, clean everything up, and put it back together with the new gaskets and bolts to get me by a few more weeks. It seems more obvious now the piston rings are shot and/or the head needs a proper rebuild (exhaust valves seem pretty rough as well) So both top and bottom end really which is going to involve good time and money. At the moment, hoping to avoid that for a bit longer. A few months time I can take the car off the road for a long time (and I want to do a lot myself as a learning exercise), but for now .. If can get it driving without it overheating, might also give me time to source a replacement engine to drop in.

    Head:



    Cylinder 1:



    Cylinder 3 & 4:


  12. #12
    Jack of all trades Automotive Encyclopaedia mattysshop's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    nice, i'd let that soak in deisel or petrol bath for a while!!

    aftermarket stem seals are fine.. last 4ag i built was about 2005... and the AE86 coupe (written off) it was in was just bought by someone on these forums.. the engine has been running fine with no issues in that department..

  13. #13
    Junior Member Too Much Toyota
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    Default Re: 4age head gasket - lend me your thoughts

    predator: get some hylomar (spell?) to spray onto both sides of hte H/G before fitting it. Given that you're only doing a re-assembly, the improved sealing from the spray may help a bit.

    Given that you've already got the motor out, I'd weigh-up pulling the pistons, giving the bores a light hone and just fitting new rings - it is burning a lot of gunk - some of which may be coming past the rings.

    Also, get the machine shop to do a simple hardness test on the head - if it's gone soft (from the multiple over-heats) then a new gasket + skim is not going to help. Personally, i wouldn't bother with the skim unless you're also going to change the valve-stem seals and lap (or reface) the valves/seats - they have to come off anyway if you're machine the face.
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    Hooligans Holiday Grease Monkey kickstartRA28's Avatar
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    Default Re: 4age head gasket - lend me your thoughts

    Sometimes its hard to know how much you should rebuild you do the top end up and it can put more pressure on the bottom end, and then uses oil blows smoke etc.

  15. #15
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    Default Re: 4age head gasket - lend me your thoughts

    ^^^ Yeah, if I did the top, a worn bottom could simply gunk it up quickly.. If I did the bottom, worn valves could cause inconsistent combustion and put stress on the bottom end. I think it would be best to do it as one.

    Quote Originally Posted by thechuckster View Post
    predator: get some hylomar (spell?) to spray onto both sides of hte H/G before fitting it. Given that you're only doing a re-assembly, the improved sealing from the spray may help a bit.

    Given that you've already got the motor out, I'd weigh-up pulling the pistons, giving the bores a light hone and just fitting new rings - it is burning a lot of gunk - some of which may be coming past the rings..
    Block is still in the car attached to the gearbox, just removed the head and everything around it. Looks like they need it, but once I put in the effort for the rings, may as well do the bearings, then may as well.. etc!

    Have cleaned up the block and the head as best I could. Is not spotless, but hopefully enough for the short-term.



    Here is cylinder 2 and 3, very gunked up:



    There is pitting on piston 3, this is matched in the head. Detonation? caused by maybe a slightly bung injector?



    Some scoring in cylinder 1:



    I picked up some Hylomar spray ($18 - Bursons) to give a try. Picked up new washers and bolts from Mr Toyota ($97 all up). Will assemble this weekend.. if I can get 10,000km more out of this engine I would be quite happy. There is only one way to find out.

    Last edited by predator; 15-01-2010 at 10:23 AM.

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