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  1. #11
    Join Date
    May 2018
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    Woking, UK
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    159

    Default How to replace a noisy tappet

    The car is fine to drive. As itís still very new to me, Iím not going to swear to anything though. It has cut out at idle a couple of times, but it restarted immediately. I suspect the plugs will be knackered. Not picking up any fault codes with the MB Star at all (from the CPS for instance).

    Back to the ticking. Planning to have a look at that tomorrow or the weekend. Actually bought a CPS anyway, so will change that and the plugs. Iíve ordered a single tappet as well just in case, so Iím reasonably prepared.




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  2. #12
    Join Date
    May 2018
    Location
    Woking, UK
    Posts
    159

    Default How to replace a noisy tappet

    Well I think I have found the source of the noise and itís not good news. Several hours spent removing the inlet manifold, coil packs and everything else out of the way to remove the cam cover. Managed to secure the cam chain by tie wrapping the top sprocket and chain and the tying that to the car. It shouldnít move so I reckon I can put it back exactly as it was. Anyway, either the cam, followers and rappers removed. Iím a bit concerned about the state of the bearing surfaces. Thereís quite a bit of scoring, the worst parts being the bearing caps and the cam itself. The bearing surfaces in the head didnít look as bad thankfully. Iím going to squeeze the rappers and make sure they are okay.

    So I think Iím looking at a replacement cam and bearing caps, Iíll try and polish the bearing surfaces in the head to smooth any areas that have scoring.

    Iíve included some pictures in case this is normal and I am overreacting?





    A question I need answering is whether the cam in the Brabus engine is the same as the regular 700?


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    Last edited by Smartysmartface; 26th January 2019 at 19:40.

  3. #13

    Default Re: How to replace a noisy tappet

    It's not great and indicative of poor maintenance in the past, but it'll likely carry on perfectly fine for a long while yet. Unlikely to be the source of the rattle unless the bearing clearance is really large (Plastigauge can be used to measure this). Polishing the cam bearing journals with some fine strip emery might not be a bad idea though.

    You should not change the bearing caps since they are exactly matched to the other half of the bearing in the cylinder by a line boring process. This means e.g. a number 1 cap from one head will not be exactly the same as the number 1 cap from another head.

    I assume "rappers" is an auto-correct of tappets rather than getting Dr. Dre to fix your head

  4. #14
    Join Date
    Jun 2005
    Location
    Aberdeenshire
    Posts
    2,088

    Default Re: How to replace a noisy tappet

    Inspect oil filter for metal particles. I would also inspect big end bearings. Check state of oil pump. A pity you did not measure oil pressure initially before opening engine out.

  5. #15
    Join Date
    May 2018
    Location
    Woking, UK
    Posts
    159

    Default How to replace a noisy tappet

    Quote Originally Posted by mikerj View Post
    It's not great and indicative of poor maintenance in the past, but it'll likely carry on perfectly fine for a long while yet. Unlikely to be the source of the rattle unless the bearing clearance is really large (Plastigauge can be used to measure this). Polishing the cam bearing journals with some fine strip emery might not be a bad idea though.

    You should not change the bearing caps since they are exactly matched to the other half of the bearing in the cylinder by a line boring process. This means e.g. a number 1 cap from one head will not be exactly the same as the number 1 cap from another head.

    I assume "rappers" is an auto-correct of tappets rather than getting Dr. Dre to fix your head
    Thanks, I had a feeling they might be matched. I think the previous owner must have run low on oil. I can polish up the bearings with some fine wet and dry. Iíll check the tappets (or rappers!) tomorrow and hopefully one will be damaged. I have a spare from Euro car parts (5.99 delivered!).

    Anybody know about Brabus engines?

    Do they use a standard 700cc cam or is it unique to the Brabus? Same for the head casting?




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  6. #16
    Join Date
    May 2018
    Location
    Woking, UK
    Posts
    159

    Default How to replace a noisy tappet

    Quote Originally Posted by tolsen123 View Post
    Inspect oil filter for metal particles. I would also inspect big end bearings. Check state of oil pump. A pity you did not measure oil pressure initially before opening engine out.
    Thanks Tolson, I did have a look at the old filter which Iíve still got, and it looked fine, nice and clean. Havenít done a compression test but the plugs all looked good.

    And yes, absolutely, I am now very nervous about the bottom end. If the cam bearings are damaged then the mains and big ends are probably as bad or worse!

    What condition are the cam bearing surfaces usually (after 76k miles)? The cam lobes themselves look brand new, no wear at all. Strange the bearings look so trashed.

    Does the MB Star pick up an oil pressure measurement or do I need to screw a gauge into somewhere?


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    Last edited by Smartysmartface; 26th January 2019 at 22:05.

  7. #17
    Join Date
    Jun 2005
    Location
    Aberdeenshire
    Posts
    2,088

    Default Re: How to replace a noisy tappet

    I strongly advise against cleaning up bearing surfaces except on camshaft but then only to remove ridges if any. Must be done on a lathe or special machine.

    Oil starvation at top of engine is cause for this type of wear. You therefore need to check condition of oil pump, oil sprayers and timing chain tensioner. Perhaps best putting engine back together and start by measuring oil pressure.

    Measure oil pressure by removing oil pressure switch and fit test gauge.

  8. #18
    Join Date
    May 2018
    Location
    Woking, UK
    Posts
    159

    Default How to replace a noisy tappet

    Quote Originally Posted by tolsen123 View Post
    I strongly advise against cleaning up bearing surfaces except on camshaft but then only to remove ridges if any. Must be done on a lathe or special machine.

    Oil starvation at top of engine is cause for this type of wear. You therefore need to check condition of oil pump, oil sprayers and timing chain tensioner. Perhaps best putting engine back together and start by measuring oil pressure.

    Measure oil pressure by removing oil pressure switch and fit test gauge.
    Okay, Iíll give that a go. I did watch a YouTube video of someone cleaning up crank pins using fine wet and dry with WD40 and a long boot lace wrapped round the w&d so he could spin it back and forth.

    Perhaps Iíll just put it all back together and save myself an hour of boredom. Can you buy test oil pressure gauges or should I try and find an aftermarket universal type?

    Iím going to inspect the tappets first thing today and hopefully one will be damaged causing my knock. One or two were tricky to get out of the head casting requiring a tug with pliers, so maybe thereís some pickup caused by bits of my bearings! That could be the source of the knock if they are sticking. Iím also going to rinse out the oil filter to see if there are any particles in there as well.


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  9. #19
    Join Date
    Jun 2005
    Location
    Aberdeenshire
    Posts
    2,088

    Default Re: How to replace a noisy tappet

    Buy an oil pressure test gauge kit similar to mine:

    Only sufficiently Smart owners have these kits.

    My kit came with a 7.2 bar max test gauge. Used it last to set pressure on an oil fired boiler. That is why in above photo the tester has a 10 bar max gauge fitted.

    Cost is around £30.

  10. #20
    Join Date
    May 2018
    Location
    Woking, UK
    Posts
    159

    Default How to replace a noisy tappet

    Thanks, Iíll have a look out. eBay seems to have plenty which go up to 500 psi whereas the range weíre interested with a car engine is more like 5-75 psi.


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