Urgent advise needed - smoke galore

[bobbrown]

Like i posted earlier, check thos oil rings.. It's very easy to get them in wrong and they will cause alot
of smoke...

Actually this type of oil ring is not that easy to get wrong.

rings.jpg

Mind you if the extract from the manual it to be believed and you fit the second ring up side down that could cause problems.
As I see it you have a compression ring, then a tapered face ring and finally an oil control ring, they should have been marked originally "top" but that may have worn off.

Bob

[Brit-Car-Nut]

Rings with a direction usually have a dot on the top side at one of the ends. They are rarely marked with ink or similar.

With our 3 ring forged pistons for the race engine, we would order 4 ring ring sets and replace the angled second ring with the extra square compression ring. Mind you that the rings are replaced after every full weekend, so they don't stay there very long. We also use steel rings and almost dry bores during the assembly (learned that from the Porsche racing crew). We "dingle brush" the bores to break the glaze and make sure they are clean and free of any grit and then pop in the pistons with a VERY faint film of lube. Moly Lube is horrible for ring seating. It is important to make sure that if you use it for the cam bearings/lifters, that you don't use too much and contaminate the break-in oil.

The oil ring has three components: the two wipers and an expander. It is easy to overlap the ends of the expander which hurts the effectiveness of the wipers.

Every manufacturer has their unique alignment for the gaps in each part, so it needs to be researched if it isn't in the workshop manual (I haven't looked in my copy).

Every time I have worked on a smoking engine that has been tampered with previously, I find standard pistons that have the ring grooves worn out or the oil ring is assembled/aligned incorrectly.

Valve Stems/Guides are a close second to the cause of failure as DIY'ers usually don't know how to check all the clearances.

Just my 2p based on several hundred engine rebuilds.

[PECKHS]

Just an update
After a long long wait the last of the parts have finally arrived. Will start to re-assemble the engine next week.
Hopefully it will turn out fine this time

[Monty]

Just an update
After a long long wait the last of the parts have finally arrived. Will start to re-assemble the engine next week.
Hopefully it will turn out fine this time

Hope all goes to plan for you

[PECKHS]

encountered a new problem whilst assembling the engine.
i have a new oil pressure sender unit, but it couldn't be fitted into the socket!! the threads don't match.
the original i had have 30/146 stamped on it, whereas the new one have 30/9 stamped on it!! going through the forum i realised that the new one with the 30/9 stamp is the correct part.
so, how come the original i had is different?? and what does 30/146 indicates?

[bobbrown]

A little puzzling as you say the 30/9 is the correct part for the Elan. I wonder if the engine has been changed at some point in it's life.
The engine number would help if it has not been altered.
Could not find a referance for a VDO 30/146 sender so what thread does it have?
If the hole is too big for the correct 30/9 you may be able to bush it to the correct size M10 x 1 but it is close to the starter motor so you would need to check that still fits.

Bob

[PECKHS]

Well, we know that the engine has definitely been changed. However, we could not determine which engine was used.
Not sure of the thread size of the original sender. I do know the Elan sensor thread size should be M10X1.
How do we measure thread sizes btw???

[Specky]

You can use a thread guage...

Just marry up the thread to one that fits on the guage. Then just read the figure off the guage.

I'll take a picture of mine

TTFN

[Specky]

TTFN

[PECKHS]

Thanks specky. Will try to search for one of those.

[bobbrown]

It could also be an NTP thread and it can get quite tricky as the NPT threads are tapered and 1/8" NPT is very close to M10 x 1 .
First thing to do is measure the diameter somewhere in the middle of the threaded section.
It can be a real pain to identify as the two threads share the same thread angle and the pitches do run close, if you convert 1/8 NPT to a metric pitch it is 0.941 as aposed to 1.
VDO senders in the UK and I am assuming it is a VDO sender, come in M10 x 1, M12 x 1.5, M14 x 1.5, 1/8" NPT and 1/4" NPT, the first three speak for them selves in terms of the diameter but the NPT threads should be 3/8" (9.525mm) and 1/2" (12.7mm) in the middle as they are tapered threads.

Bob

BTW the thread gauges for NPT are different as it is an imperial size.

[PECKHS]

just a thought...
if i can't get the proper sender with the correct thread, how feasible is it if i was to fabricate an adapter?
will it affect the operations of the sender, and the readings? as the sender will not be in the correct position in the block...
something like in the file posted.... pardon my crude drawing

[bobbrown]

Adapters/bushes are available and will not affect the operation, but as I said you will need to check the starter motor still fits.

[PECKHS]

the engine re-assembled, less the oil pressure sender. still can't find a appropriate one to replace the old oil sender

http://i132.photobucket.com/albums/q20/ ... G_2886.jpg

an adapter may be out of the question as it is a very tight fit...

http://i132.photobucket.com/albums/q20/ ... G_2882.jpg

[bobbrown]

So what thread is the hole in the block, with out knowing that it is going to be difficult to offer any help

Bob

[PECKHS]

So what thread is the hole in the block, with out knowing that it is going to be difficult to offer any help

Bob

The machine shop I went to did not have the tool to check the thread, so I gotta find a time to pop by and pick up the sensor and search for other shops that can and have the appropriate.
Been extremely busy these days, which definitely isn't helping

[bobbrown]

What kind of machine shop are you using?
They should have the right tools to measure threads and even with out them you can still work it out just takes a bit more skill.

If you/they do not have a thread gauge and you need the one with the correct pitch for the thread you are trying to measure be it metric, american, or whitworth to name a few as there as some specials. Then you can work it out, takes a good eye and a pair of calipers, cheap digital will do and they are a good tool to have in in any case.

caliper a.jpg

With this you can measure the diameter and if you measure it at the begining and end of the thread and the figures are different then it is a tapered thread.
Next you need to measure the number of threads over a given length which will give you the pitch, a M10 x 1 will give you 10 threads over 10 mm and 1/4" NPT will give you 18 threads per inch or 9 per 1/2".
Once you know what thread you are dealing with it is a simple matter of selecting the correct part as most if not all the VDO oil pressure senders are similar in their output (180 ohms FSD I think) and some have an oil pressure switch others do not.
If the sender needs an adapter then you still need to know the threads.

If you can measure the threads and post them then we can work out what we are dealing with.

Bob

[PECKHS]

Oh, I do have a micrometer, however it is not digital.
Didn't know the thread could be measured this way.
I'm trying to get some time to pop over to the machine shop this Friday.Hopefully I'll be able to get the measurements then.
Tks a million.

[bobbrown]

micrometer is fine, does not have to be digital, 0-1" or 0-25mm either will do.
Counting the threads is the tricky bit.
If you post your findings then it can be worked out, also a picture of the thread may be useful if you place a rule along side to get a scale I can probably work it out by scaling the picture in AutoCad.

Bob

[PECKHS]

ok, took back the oil pressure sensor.
did a measurement, the tip of the thread is abt 9.3mm, the base is 10mm. so can i assume it's tapered.
i tried to measure the threads, but couldn't come to a conslusion.
engraved on the sensor i removed from the engine are these markings
1. A100N0002F
2. 1.97
3. 30/146
4. 0-10 bar
5 0.6 + 0.2 bar (should be a +/- sign)

some pics -




the one on the right is the new sensor