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trampintransit
Joined: 09 Aug 2010 Posts: 166 Location: Edinburgh
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Posted: Sun Aug 27, 2017 11:02 pm Post subject: Curing blow-by |
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So...Engine been laid up for unknown period. Been running on and off during body restoration over two years. Engine always seemed great...now it's on the road however it's become clear it's blowing-by ..big time. ...smoke pours out if the crankcase breather and rocker cover vents at speed, even more so under load.
... After about a hundred miles or so I'd have thought that if it was sticky rings, they'd have started to free off by now? I've still to try the releasant / seafoam / atf whatever down the hot bores and leave it overnight ..but I'm not holding out for that one.
So...to what extent am I rebuilding the engine to cure the problem? I've never done this before so I'm a bit clueless. .. Can I just get away with honing the bores with the engine in the car? If not ...can it be rebored in situ by clever people with clever tools? ( It is by all accounts a absolute of an engine to get out ) ...the pistons are gonna have to be dropped so...can the shells be reused? ..
This is gonna be expensive isn't it? _________________ '60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!! |
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peter scott
Joined: 18 Dec 2007 Posts: 7119 Location: Edinburgh
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Posted: Mon Aug 28, 2017 4:37 pm Post subject: |
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If the pistons need to be taken out the bottom then you need to know if you can get them past the crankshaft. If not then you really need the engine out to remove the crank.
If you can get the pistons out there is no problem honing the bores assuming that all they need is glaze busting so that the new rings bed in. Clearly you will need to clean out any hone dust from the crank and crankcase before reassembly.
There used to be firms that offered re-boring in situ but I can't say I've seen anyone offering that service recently.
The shells can certainly be reused if you had good oil pressure before you started but replace them in the same places as them came from.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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trampintransit
Joined: 09 Aug 2010 Posts: 166 Location: Edinburgh
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Posted: Thu Aug 31, 2017 8:50 pm Post subject: |
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Thnks for that..I've been tossing all manner of stuff down the bores the last few days to see if it free the rings ( If it IS stuck rings)
What surprises me is that the plugs come out clean as a whiste? Surely if the rings were knackered or the bores really worn then I'd expect the plugs to be black n sooty? _________________ '60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!! |
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petelang
Joined: 21 May 2009 Posts: 444 Location: Nottingham
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Posted: Thu Aug 31, 2017 11:10 pm Post subject: |
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Compression test first. Maybe it's just one cylinder? Maybe valve guides?
Peter |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4105 Location: South Cheshire
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Posted: Fri Sep 01, 2017 8:01 am Post subject: |
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petelang wrote: | Compression test first. Maybe it's just one cylinder? Maybe valve guides?
Peter | Combined with a vacuum test, if the rings are worn or you will get a low reading at idle.
Both simple tests that can be performed quickly & cheaply. If you have access to a compressor , a leak test would be useful.
Dave |
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peter scott
Joined: 18 Dec 2007 Posts: 7119 Location: Edinburgh
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Posted: Fri Sep 01, 2017 10:26 am Post subject: |
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ukdave2002 wrote: | If you have access to a compressor , a leak test would be useful.
Dave |
That's an interesting idea. I'd never thought of that before. Just need to make a spark plug adaptor.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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roverdriver
Joined: 18 Oct 2008 Posts: 1210 Location: 100 miles from Melbourne, Victoria, Australia
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Posted: Fri Sep 01, 2017 11:26 am Post subject: |
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Peter, one of the older style spark plugs in which the porcelain is held in place by a threaded ring, as in earlier KLG., is your starting point. The other component is a valve from a tyre inner tube. Disassemble the plug, replace the porcelain with the tyre valve and you have a very inexpensive adapter. _________________ Dane- roverdriver but not a Viking. |
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peter scott
Joined: 18 Dec 2007 Posts: 7119 Location: Edinburgh
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Posted: Fri Sep 01, 2017 12:54 pm Post subject: |
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Thanks Dane, I have a small collection of detachables and might sacrifice one.
I also have this that popped out of a brand new Michelin tube.
Peter
_________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4105 Location: South Cheshire
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Posted: Fri Sep 01, 2017 3:03 pm Post subject: |
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Leak-down testers have plummeted in price, this one is less than £18 delivered:
Dave |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Fri Sep 01, 2017 3:23 pm Post subject: |
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That looks like a neat piece of Kit and for £18. What's that, a decent bottle of wine ?
There is so much stuff available today, OK some of it can be a bit naff and cheap but I guess it can depend on how often it is going to be used.
I know, for some of us, there is a certain challenge and satisfaction in making things. but perhaps it hawks back to the days when sometimes DIY was the only viable option.
I remember my Dad turning up oak pulleys and cutting side plates out of old bits of chassis to make pulley blocks for our first scaffold pole tripod used to pull the engine from his first 105E. My hydraulic engine crane cost me $180 Cdn about £100. I used it not so long ago to help pull a tree stump and once used it to hold up a deck on our house while I put in a new support pillar. |
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