Urgent advise needed - smoke galore

[PECKHS]

Come to think of it, how do we check whether the oil pressure sensor is working fine?
The reason I am changing it was because the oil prssure lamp was on intermittently. However, that was when my engine was smoking...
Should I take a risk and put back the original?

[bobbrown]

If my scaling in AutoCad is correct and the measurements correct then in my opinion the original is 1/8 NPT.
Now I'm a little confused as SJ's website shows the sender with the markings of 30/9 now that corresponds to a M10 x 1 thread but the part number is A100N0002F which is what is stamped on your sender. I suppose they could have used a generic picture and picked the wrong one as that scaled in AutoCad is M10 x 1.
M10 x 1 and 1/8 NPT are very close to each other dimensionally and if my research is correct then the sender is this one
Pressure 0-150 PSI (10 bar)
Thread 1/8-27 NPT
Switch pressure 11.4 PSI (0.79 bar)
30/15
360 025

30/15 I'm a little unclear about but the last one is a VDO part number.

If you were getting the oil light flickering and the gauge was working then I doubt the sender was faulty and probably an engine/oil issue, I assume it was only on intermittently when the engine was hot. One question would be what oil was it running on?
The engine is supposed to have minimum oil pressure of 0.35bar at warm idle according to the manual seems a bit on the low side to me and the switch operates before then anyway.
As long as the gauge was working and I assume the intermittent oil light was showing low on the gauge as well then I would think the sender is OK, problem is it's a pig to get at once the engine is back in.

Bob

BTW the Lotus part number also corresponds to an Elise sender and I know the K series engine is ported 1/8 NPT

[PECKHS]

tks bob for the information.
i will be popping by the local VDO vendor later. the friendly chap working there has requested to see the original sensor. hopefully he'll be able to help me. he was saying it might be an OEM item... although i don't really understand what he meant by that.
the engine light was on intermittently previously, and it was on when the engine was overheating(think you'll remember my post abt the overheating engine), and when the engine was stalling. i wanted to change the sensor as a 'just in case' measure since the engine was out. as you've said, it really will be a chore to change it after the engine has been re-installed in the car.
will keep posted
cheers

peck

i was just wondering. we are very sure the engine has been changed. but which engine was used? could it be a 4XE1W from the isuzu impulse rs which was used as a replacement ??? could the 4XE1W have used a oil pressure sensor with a different thread???

[PECKHS]

ok, got a new sensor, this time with the 1/8 NPT



a comparison



hope it fits

[tigerdog]

i was just wondering. we are very sure the engine has been changed. but which engine was used? could it be a 4XE1W from the isuzu impulse rs which was used as a replacement ??? could the 4XE1W have used a oil pressure sensor with a different thread???

Check out the Hot to Trot thread. A few years back, Doc Fizzix bought an Isuzu engine and rebuilt it for use in his Elan. He carefully cataloged the differences he found between his engine and the Lotus item. Maybe the sensor is mentioned.

[PECKHS]

i was just wondering. we are very sure the engine has been changed. but which engine was used? could it be a 4XE1W from the isuzu impulse rs which was used as a replacement ??? could the 4XE1W have used a oil pressure sensor with a different thread???

Check out the Hot to Trot thread. A few years back, Doc Fizzix bought an Isuzu engine and rebuilt it for use in his Elan. He carefully cataloged the differences he found between his engine and the Lotus item. Maybe the sensor is mentioned.

hi tigerdog, went thru the thread but there's no mention of the oil pressure sensor

anyway, the workshop has picked up the new sensor and i'll know the good(or bad) news within the day

[PECKHS]

bad news, new sensor didn't fit

gonna try one last time next week by going to some big spare parts shops in town and try to look for an alternative from a japanese car

if nothing suitable is found i will have to take a bet and use back the original sensor

correct me if i'm worng... the oil pressure sensor is a reading device only, or does it has other functions? other than sending signals to the pressure gauge and oil pressure light, does the ECM relies on the signal/voltages to control and/or regulate the engine?
can the elanscan read the oil pressure?

getting extremely restless with the no-go elan. i really must take a drive in it to rekindle the feelings i had when i just bought the car...

[muley]

bad news, new sensor didn't fit

gonna try one last time next week by going to some big spare parts shops in town and try to look for an alternative from a japanese car

if nothing suitable is found i will have to take a bet and use back the original sensor

correct me if i'm worng... the oil pressure sensor is a reading device only, or does it has other functions? other than sending signals to the pressure gauge and oil pressure light, does the ECM relies on the signal/voltages to control and/or regulate the engine?
can the elanscan read the oil pressure?

getting extremely restless with the no-go elan. i really must take a drive in it to rekindle the feelings i had when i just bought the car...

It's just a reading device.

It was flickering because the oil pressure was going down because the engine was shot.

My guess (well 99%) is that the old one is fine.

Rgds

Jim

[saska]

correct me if i'm worng... the oil pressure sensor is a reading device only, or does it has other functions?

No it has a terminal which feeds the oil press warning light and a terminal that feeds the oil press guage.
Wiring is:
Terminal marked G == White / Brown stripe (Gauge)
Terminal marked WK == Brown / White stripe (Warning Light)

other than sending signals to the pressure gauge and oil pressure light, does the ECM relies on the signal/voltages to control and/or regulate the engine?
can the elanscan read the oil pressure?

No. There is no connection from oil sender to ECM

[bobbrown]

As I see it there is a choice of three, all very close to each other and with out the actual part to measure very difficult to say what the thread is as they are too close to call with pictures.

M10 x 1 diameter 10mm thread pitch 1mm 25.4 threads per inch
1/8 NPT tapered thread nominal diameter 9.49mm pitch 0.94mm 27 threads per inch
1/8 BSPT tapered thread diameter 9.72mm pitch 0.907mm 28 threads per inch

As you have tried two out of the three there is only one left unless it is a special, so does it look like the two you have tried are too big?
A bit more research does show the impulse RS with a BSPT pressure switch.
May be there is a local precision engineering company that could identify the thread for you and resolve the issue once and for all.

Third time lucky.

[PECKHS]

Tks for all the replies guys.
I have spoken to an engineering firm, and they claim that they are able to machine an adapter to fit the sensor. There should be just enough clearance. Gonna meet him tomorrow.
At the same time, will call up VDO again also to check if they have any suitable sensor with the 1/8 BSPT thread.
Who knows, as bob said, I might be third time lucky

[PECKHS]

well, went thru the VDO product catalog, apparently there is only ONE pressure sender with the 1/8" 28 BSP thread, but it's a single terminal unit. so there's no line to the warning light.
will see what the engineering workshop says...

[Brit-Car-Nut]

I think we are all curious: What exactly doesn't fit?

Is the SENDER thread too small so it doesn't fill the hole in the block? Is it too big so it won't even start in the block? Does it start but not thread more than a couple of turns?

You have the original switch, right? I can't believe nobody can tell you what the thread is on the switch that came out of the block.

Just saying it won't fit is not enough information. The "original" switch you have pictured: is it the switch from the engine? If not, where is that switch.

If it is, it has the Lotus part number stamped on it, so how is it Lotus says it is a 1/8" National Pipe Thread, yet you can't make it fit? If the old one came out, a similar one will go back.

Any chance you are looking at the wrong hole?

Don't be mad at my question, I have seen decent mechanics work for hours on a wrong assumption. No insult implied or intended, really.

You should be able to get a M10 x1 standard bolt fairly easily and 1/8 NPt brass fittings are common (at least in the US), so you should be able to use one of them to test the hole.

Basically, if the sender is smaller than the hole, then it has to be either a 10mmx1 or 1/8 BSPT hole (the 1/8 NPT is the smallest diameter of the lot) so a M10 bolt should clear up the mystery.

If the sender is too big to fit in the hole, then it is either an M10x1 or 1/8 NPT hole and again, the M10x1 bolt should answer the question.

If the sender is too big for the hole, why not look into having the sender turned down and re-threaded to the correct thread?

Here is a link to a supplier that has a lot of adapters available: BSP Male to AN or NPT Male Adapter

[bobbrown]

VDO list a BSPT sender with a warning contact over here!
Range /Thread /Warning Contact/# On Sender/ Part No.
0-150 PSI /1/8-28 BSP/ 7.0 PSI/ 30/66/ 360 083

As for an adapter for the hole then you need male for the block and female for the sender so the parts listed by Brit-Car-Nut would require another adapter as the ones shown on the link are male/male.

May be a case of using the old sender and seeing if you get a reading on the gauge and the light go out when you turn the engine over for the first time to get the oil pressure up before firing it up.

Bob

[PECKHS]

ok, to make it clear, the original oil pressure sender removed from the engine block has a very different thread from the part listed in Sj sports.
The one from Sj sports is a M10X1. However, it starts but only turn a couple of thread. Likewise with the 1/8" 27 NPT sender I bought after that.
Went to a precision engineering shop today, and the original sender i removed from the engine block is 1/8" 28 BSP.
there is no suitable sender from VDO, so i asked the shop owner to fabricate an adapter. will cost me abt GBP15.
should be able to pick it up tomorrow.
the shop will be using copper to fabricate the adapter... will using copper instead of brass going to be an issue??
tks

peck

[PECKHS]

VDO list a BSPT sender with a warning contact over here!
Range /Thread /Warning Contact/# On Sender/ Part No.
0-150 PSI /1/8-28 BSP/ 7.0 PSI/ 30/66/ 360 083

Bob

that's weird, i couldn'y find this in the product catalog...
will call up the VDO guy tomorrow.

[bobbrown]

The shop will be using copper to fabricate the adapter... will using copper instead of brass going to be an issue??
tks

peck

Copper seems a strange choice of material and I would be a little cautious as copper does work harden and could break, I would have gone for steel as a first choice, brass may be second.

Bob

[Brit-Car-Nut]

Sorry. Grabbed the wrong link. From that page there is this link: BSP adapters

There is one for 1/8 BSPT to 1/8 NPT: 1/8 NPT Female to 1/8 BSPT Male

I would also look into getting a M10x1 sender and getting it re-tapped to the 1/8 BSPT as the M10x1 is a bit larger in diameter.

[PECKHS]

sorry, the material used is brass, not copper. the old man couldn't speak english, and told me the term in mandarin. had to translate it in my english-chinese dictionary... hahah

Sorry. Grabbed the wrong link. From that page there is this link: BSP adapters

There is one for 1/8 BSPT to 1/8 NPT: 1/8 NPT Female to 1/8 BSPT Male

I would also look into getting a M10x1 sender and getting it re-tapped to the 1/8 BSPT as the M10x1 is a bit larger in diameter.

i do have the M10x1 sender. the reason why i decided to fabricate an adapter is so that i(or the next owner if i decide to sell it) will be able to get the correct replacement in future without going through what i am going through now.

[PECKHS]

VDO list a BSPT sender with a warning contact over here!
Range /Thread /Warning Contact/# On Sender/ Part No.
0-150 PSI /1/8-28 BSP/ 7.0 PSI/ 30/66/ 360 083

spoke to the local VDO office. apparently 360 083 is a controlled item and only available in the US that explains why it is not available in the product catalog... geezzz