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Author Topic: Mechanic School Blog  (Read 94112 times)

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Webby the Bear

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Re: Mechanic School Blog
« Reply #90 on: 24 September 2012, 21:08:27 »

Day 12 (Today): Help and input from you guys in red  :y ;D

Well, another awesome day of just practical  8) 8) 8)

So I finished off putting the collets back on to the valves (I had just two left from last week) using the valve spring compressor. just a brief reminder that we'd got the valves out so we could ''lap them in'' which means we were using that grinding paste to make the seat perfect........We then put the HG on the block and then the head and then torqued it up... standard spiral to 30nm, 90o, 90o. we then put the pushrods back in, then the rocker shaft.

We then got the engine hoist out to lift the engine back up on the stand.... i did tell my mate to get out of the way as he was ruining the shot  ::) Also was interesting that the engine didn't have its own lifting eyes but they had a box of them. we simply found two, put one through an exhaust manifold stud, and the other on an intake manifold stud, put nuts on them and began lifting ;)



So then when we'd put our engine back we had purposely left the valve cover off as our teacher showed us how to gap the valves. a note worth making for reference is that the inlet valves are always bigger than the exhaust valves so they can pull more mixture in. also if the exhaust valves were as big (or bigger) apparently they would get too hot..... got to be honest not too sure why  ???
Anyhow because the exhaust valve expands more in use we set that at 0.3mm and the inlet valve gap at 0.2.... when i say gap i mean the gap between the rockers and the top of the valves  :y and we used these feeler gaugers (i think thats what theyre called) to get the right gap.......
(this pic was actually taken from our second valve gapping job which we actually did on an engine in a car... another Ford Fiesta) its also worth noting that the bolt the socket is on we simply tightened if there was too much of a gap and unscrewed that if we wanted to make a bigger gap if it was too close). one final note is that the gapping of valves is mainly done on pushrod engines as most SOHC & DOHC have hydraulic lifters that are serviced differently and ultimately dont need gapping.
ooooooooooh one really important thing i nearly missed....... to do the gapping on we had to have the valves we were working on with that cylinder at TDC on compression stroke. and we used a method called ''ON THE ROCKS''  8). And it goes like this....
Cylinder 1: we turn the engine by hand and watch it's sister cylinder (cylinder 4) close it's exhaust valve and just open it's inlet valve. we now know cylinder one is at TDC and on it's compression stroke and therefore we're ready to gap cyliner 1. repeat for other cylinders.


This is a pic of the Fiesta Engine. note the battery is missing, however due to some good old charm and a bit of persistance i got a battery... and the keys  8) I have to say that even though i didnt hear the car before we'd done the job it sounded really sweet after the job!
A note about this engine which i completely didnt understand.... you see the oil filler cap.... there are two pipes going from this in to the intake. one you can see (short thin pipe to the left) and then one thick pipe which you cant see going from the oil filler tube to the right near the MAF on the right near where the battery should be. any ideas why this is?????


ok, so then we moved our trail of destruction mechanics skills to a corsa  ::). 4 pot, DOHC.....


Took the valve cover off this bad boy...... how many fekking bolts  :o and were greeted with.....(soz for the shite photo)


now this was interesting. the teacher rushed this a bit so i didnt quite get it so if anyone cares to explain that would be great. but basically we got a small screwdriver and under each cam lobe (when both dual cam lobes weren't opening valves) we pushed something to the right and back in place. if it clicked, which they all did, they were good  :-\ :-\ :-\ :-\ :-\ sorry for the crap explanation but i'm struggling myself with what happened  ;D

Anyway thats enough action for one day. some good work done. will update tomorrow as we hae more practical  8) 8) 8) 8) 8) 8)

Car Bear


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Kevin Wood

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Re: Mechanic School Blog
« Reply #91 on: 24 September 2012, 21:16:28 »

The pipes into the oil filler cap are the crankshaft breathers on this engine... They're not very effective, and Ford owners don't believe in oil changes, so you'll normally find a large buildup of very black margarine under the rocker cover. ;D
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Webby the Bear

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Re: Mechanic School Blog
« Reply #92 on: 24 September 2012, 21:18:46 »

Two quick things I forgot to mention....

1. when we'd done our valve gap job on the fiesta we'd put the HT leads round the wrong way... they weren't numbered sadly. however when we started it up it woudn't idle  ??? however when i put them the correct order it idled sweetly at 1000rpm. why is that? i thought we'd just be down a pot on power and maybe hear a machine gunning type sound as the sparks fly???

2. on that corsa valve cover is a gasket very similar to the CC Gasket for the mig. however those half moons were at the front of the engine so very easy to see whether they were sat in place correctly  :y
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Webby the Bear

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Re: Mechanic School Blog
« Reply #93 on: 24 September 2012, 21:20:31 »

The pipes into the oil filler cap are the crankshaft breathers on this engine... They're not very effective, and Ford owners don't believe in oil changes, so you'll normally find a large buildup of very black margarine under the rocker cover. ;D

 ;D

Thanks Kevin. why circulating back in to the intake though? i asked if this was this cars version of EGR but i was told a definite no. but thats what it sounds like  ???
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Marks DTM Calib

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Re: Mechanic School Blog
« Reply #94 on: 24 September 2012, 21:23:08 »

Oh yes, setting the valve clearances on those engines is pretty hopeless using feeler gauges.

The ony effective way is with gauge wires whilst presing gently on the adjuster bolt as the rockers are shite and wear grooves in them where they rub on the valve stem tops.......and hence why most KA's rattle (they have this dog of an engine that should have been retired 25 years ago!).

With leads wrong, you wont be lighting the fuel mix (if at all!) on the correct cycle (remember your suck-squeeze-bang-blow)

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Marks DTM Calib

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Re: Mechanic School Blog
« Reply #95 on: 24 September 2012, 21:24:34 »

The pipes into the oil filler cap are the crankshaft breathers on this engine... They're not very effective, and Ford owners don't believe in oil changes, so you'll normally find a large buildup of very black margarine under the rocker cover. ;D

 ;D

Thanks Kevin. why circulating back in to the intake though? i asked if this was this cars version of EGR but i was told a definite no. but thats what it sounds like  ???

Crank case gases have to be re-cycled via the inlet for 'environmental' purposes, years ago they were vented to atmosphere resulting in oil spraying about and gases escaping.

They are (trying) to do the same job as the breathers on the Omega
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Webby the Bear

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Re: Mechanic School Blog
« Reply #96 on: 24 September 2012, 21:27:03 »

That all makes sense, thanks Mark. so if we consider this as an ''accompaniment'' to the EGR that the omega has?

as for the 4 stroke cycle, yes thats true... if i'd mixed the minimum amount of leads that would mean the spark plug isnt igniting on at least two cylinders. soz its been a long day  ::) :y
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Re: Mechanic School Blog
« Reply #97 on: 24 September 2012, 21:28:27 »

The pipes into the oil filler cap are the crankshaft breathers on this engine... They're not very effective, and Ford owners don't believe in oil changes, so you'll normally find a large buildup of very black margarine under the rocker cover. ;D

 ;D

Thanks Kevin. why circulating back in to the intake though? i asked if this was this cars version of EGR but i was told a definite no. but thats what it sounds like  ???

I can't remember exactly how it works as, thankfully, my days of maintaining that car ended when it was made a couple of feet shorter. ;D

Incidentally, it had tried to kill itself once before that when the oil got into such poor condition that one of the big ends seized and it suffered a leg out of bed (connecting rod through the side of the block leaving a fist-sized hole).

I think you'll find one of those breather pipes comes from before the throttle, I.E. air filter box or ducting, and one comes from a small jet after the throttle, i.e. the throttle body or intake manifold. It's simply a case that one pipe creates a slight vacuum from the intake manifold at idle or closed throttle and the other takes over at open throttle from further up the intake when there's no vacuum in the intake manifold,so the engine is ventilated in all operating conditions.

This is exactly how the Omegas system works, just laid out differently.
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Re: Mechanic School Blog
« Reply #98 on: 24 September 2012, 21:31:51 »

EGR is doing a slightly different thing, by the way.

EGR is a connection from the exhaust manifold to the intake manifold that can open under certain conditions. It means the engine is burning a mixture of fuel, air and exhaust gases instead of just fuel and air. This lowers the temperature of combustion giving better exhaust emissions and also gives a small improvement in fuel consumption when lightly loaded.
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Webby the Bear

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Re: Mechanic School Blog
« Reply #99 on: 24 September 2012, 21:32:29 »

The pipes into the oil filler cap are the crankshaft breathers on this engine... They're not very effective, and Ford owners don't believe in oil changes, so you'll normally find a large buildup of very black margarine under the rocker cover. ;D

 ;D

Thanks Kevin. why circulating back in to the intake though? i asked if this was this cars version of EGR but i was told a definite no. but thats what it sounds like  ???

I can't remember exactly how it works as, thankfully, my days of maintaining that car ended when it was made a couple of feet shorter. ;D

Incidentally, it had tried to kill itself once before that when the oil got into such poor condition that one of the big ends seized and it suffered a leg out of bed (connecting rod through the side of the block leaving a fist-sized hole).
I think you'll find one of those breather pipes comes from before the throttle, I.E. air filter box or ducting, and one comes from a small jet after the throttle, i.e. the throttle body or intake manifold. It's simply a case that one pipe creates a slight vacuum from the intake manifold at idle or closed throttle and the other takes over at open throttle from further up the intake when there's no vacuum in the intake manifold,so the engine is ventilated in all operating conditions.

This is exactly how the Omegas system works, just laid out differently.

 :o :o :o :o ;D ;D ;D ;D

got to say though they're really easy to work on compared to my omega  ::)

but thanks fir that explanation.... it all makes perfect sense!!!  :y

distributor is in a weird place though, RIGHT UNDER the intake manifold - would be a bugger to get to
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Webby the Bear

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Re: Mechanic School Blog
« Reply #100 on: 24 September 2012, 21:34:16 »

EGR is doing a slightly different thing, by the way.

EGR is a connection from the exhaust manifold to the intake manifold that can open under certain conditions. It means the engine is burning a mixture of fuel, air and exhaust gases instead of just fuel and air. This lowers the temperature of combustion giving better exhaust emissions and also gives a small improvement in fuel consumption when lightly loaded.

cheers mate. i knew my friends at OOF would put me on the right track  ;D :y :y :y

difficult at times trying to get all the info you need when the teachers are having to spend a lot of their time bollocking kids running round with windy guns pretending to be in Die Hard  ;D ;D ;D ;D
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Re: Mechanic School Blog
« Reply #101 on: 24 September 2012, 21:36:41 »


distributor is in a weird place though, RIGHT UNDER the intake manifold - would be a bugger to get to

Yep, it's also a bugger when you have a crossflow engine on carbs and the carburettor starts leaking fuel onto the distributor (which contains sparks, of course). Just another way these engines attempt suicide. It's a good job most are now injected. ;D
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Marks DTM Calib

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Re: Mechanic School Blog
« Reply #102 on: 24 September 2012, 21:37:22 »

Dizzies are a nightmare on them (although the Endura engine had a DIS pack) as are plugs.........right upto final production Ford still used tapered seat plugs which are nicly positioned at the front where the wet and shite sprays.

I have actualy had to bin two heads off these when plugs sheared off on removal and NOTHING would get the remains out!

Its a good job the head can be changed in an hour!  ;D
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Webby the Bear

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Re: Mechanic School Blog
« Reply #103 on: 24 September 2012, 21:37:55 »

By the way, I completely forgot to mention some more good news...... I got an ''outstanding'' on my first assignment  :) :) :) :) :) :) that H&S one I mentioned.

just toying with the idea of posting it up...... but then it may send peeps to sleep  :-\ ::) :y
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Re: Mechanic School Blog
« Reply #104 on: 24 September 2012, 21:38:25 »

Search on here, I and a few others have explained a few times what EGR does (might even be in the FAQ section)
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