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| Mr Brooksy |
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Hi guys,
My BA NA I6 had a leak down test done this week stating that 2 cylinders where down on pressure. What I want to know is: what tests do I need to do to test and diagnose what problem my engine may have? Other info on my situation is: Catch can fitted with no oil found in it. Isnt blowing smoke. Oil smells normal. No oil coming out anywhere. No oil fumes either. Turbo fitted running 12 pounds of boost with no running issues. Also if anyones in Newcastle NSW do they know anyone who can do these tests? Thanks guys
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| Johnson stroker |
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Do a comp test. 20% variance across all cylinders is an acceptable variance. What prompted you to get a leak down test? what is the issue you are having to warrant one?
More info please.
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| Mr Brooksy |
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I had the valve springs replaced and the place did a quick leak down test. Once done they said that it shouldnt go on the dyno and I should take it home and stop driving it til I fixed/replaced the bottom end.
Im just wondering how I can properly diagnose what the issue might be to sort the right part. Especially since the car runs well and doesnt feel wrong in any way. Ive also heard these engines can often have this problem and be completely fine.
_________________ His: 2007 FPV F6 Typhoon, Neo. |
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| Snort Performance |
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the vehicle runs fine under both boost and n/a ( up to 12 lbs ) with no evidence of blow-by or oil in the catch can? , a leak down test was performed after the valve springs where fitted which yielded a poor result 3 of of the 6 , the engine was not run after the valve springs where fitted
so to confirm the engine has piston/ring damage what would be the correct method/test to undertake to determine the actual fault? would a leak down test be sufficient? also should the engine be run after installing the valve springs before such a test should be carried out?
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| Johnson stroker |
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Take if for a second opinion, If you get no love go to a Ford Specialist like CMS, they will not only tell you what they are doing, but why and what they hope to achieve. They are a pretty common car so there is alot of info out there about them, you still need to talk to the right people.
Is it a local guy that just does cars in general? or is it a specialist that should know what he is banging on about when it comes the these cars specifically?
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| Mr Brooksy |
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Oh and I thought this might be useful too.
The guy changed the springs then did the leak down test. Then put the cover and garnishes back on. This is when I was told there is possibly a major issue with the bottom end and that I should get a replacement etc. Is this the correct way to test for this issue? And would they need to do a compression test to make this call? Or does more need to be done to determine that the bottom end is stuffed and that I shouldnt drive it til I get it sorted?
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| Gab1 |
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Compression test, vacuumn gauge check, cooling system pressure test, do those & go from there.
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| Mr Brooksy |
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Gee you guys are quick... I guess its easy to be faster than me typing on my phone! Hahaha!
The guys who told me this are a group who really should be in the know. Quite a well known tuning company... name not important atm.
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| Johnson stroker |
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They are not at Thornton are they? Anyways, as suggested by Gab, Comp, Vac and pressure test.
You gotta remember that 4.0l motors are pretty big bores with big slugs in em, getting a good seal while the motor is static is quite difficult. leak downs look at the total seal, you could have a bit or a worn seat that is allowing pressure loss, I would doubt a head gasket, but a Co2 test will find that, Quote: The neat thing about a leakage test (as opposed to a compression test) is that it's faster and easier to figure out where the pressure is going. If you hear air coming out of the tailpipe, it indicates a leaky exhaust valve. Air coming out of the throttle body would point to a leaky intake valve. Air coming out of the breather vent or PCV valve fitting would tell you the rings and/or cylinders are worn. So why they did this yet didn't tell you where they suspect the leak to be coming from and on what cylinders is a bit perplexing. As mentioned before, 20% variance across all 6 cylinders is acceptable, ask more questions of them or talk to someone else.
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| Mr Brooksy |
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No not in Thornton
 ... not a fan of them after some "work" done previously.These guys were MUCH bigger in Sydney, with a good rep... but no names. I have been talking with a local mechanic and he thinks its quite "perplexing" too.
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| Johnson stroker |
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they could have not had the pistone at TDC as well? yeah, with out a second opinon and a more informed answer as to where the air is leaking, there is not much more that can be advised.
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
A random leak down test is IMO the most useless test you can perform on an engine.
Even more so after messing around with things like valve springs. All a leak down test will tell is how well the rings seal against the wall at the particular position they are at with a cylinder pressure that is less then 1/10th the peak pressure it would normally see. If you get a poor reading you can turn the crank 10degrees and the reading will change. The only time I even take my leak down tester out the box is if I get a very low compression reading and want to know where the leakage is. Take the car home, drive it for a while and get a HOT compression test done. If the results are ok, then you have nothing to worry about. |
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| Mr Brooksy |
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When I get back from a leaders meeting in QLD (all next week) I will get it to a mechanic mate who will do all the necessary tests.
Who by the way seems to think I was being "led on a bit". I also gave it a hard run today... didnt miss a beat. Again no oil in catch can etc as before.
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| Johnson stroker |
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Straight down the garden path.
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| Mr Brooksy |
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Sorry I should have updated this.
I had compression tests etc done on the engine to show what I already knew, the engine is ok. But it is down on compression in cyl 6 some 20%+. The others are pretty good for a motor that's had a hard run. So I need to contact Crescent Motorsport and see if they will be straight up with m or not and do the job.
_________________ His: 2007 FPV F6 Typhoon, Neo. |
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