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Old 01-07-2010, 09:24 PM   #1
dbarton
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Default Battle of the Oil Pressure Sender

I've been battling this for weeks.... When I installed a 100A (Bosch) alternator in my 242ti I relocated the oil pressure sender using a couple different angle fittings. I was using original size belts (10 x 925), so there is not very much room behind the alternator. I should note that I have done this kind of mod many times over the years and relocating the oil sender is not (usually) a hard topic. Until now.

My first issue came a week later after I snapped an alternator mount bolt while driving. turned out I had the adjuster mount at a slight angle, creating side tension on the bolt. The motor developed an oil leak at the same time. Repair and realignment of the bracket completed. Tearing it apart to find the leak, I found that the brass fitting I used that was going into the block had cracked the threaded portion right at the block. Upon disassembly, of course the threads broke off in the block, but I did get them out with an easy-out.

My guess was that when the alternator came loose and was close enough to smack the sender, cracking the fitting... or so I thought at the time.

So... a week after that fix, my 242 develops another serious oil leak. Smoke coming off the exhaust, etc. Once I park it, I find a 12 inch puddle underneath. So I tear it apart yet again and did as seen below.


The above fix lasted a little over a week.

For this fix above I used a Volvo fitting into the block, since I noticed it was a bit thicker than the first brass fitting that cracked. Alter removing the alternator this time and starting the motor, I verified the leak was coming from the threads going into the block.. hard to miss, it was a good size leak. When it was installed, I had definitely made that fitting tight, but now it was slightly loose. It did not appear cracked, but oil was definitely pouring past the threads. So I pulled it all out and replaced with all new fittings... below pic:


By now I had surmised the engine vibration was doing something bad to the junction between the block and first fitting. That's the reason for that big zip-tie holding the sender to the heater tube. This genius repair lasted a whole TWO WEEKS.

During disassembly yesterday, I found the threaded portion going into the block severely cracked and it broke off in the block creating yet another PIA.

While doing a google search on the subject, I found this interesting bit of wisdom....

Quote:
Tapered pipe fittings are prone to leakage because they are torque-sensitive. Over-tightening can distort the threads too much and create a leakage path. Also, tapered pipe threads are prone to loosening when exposed to high vibration and wide temperature variation. Repeated assembly and disassembly only aggravates the leakage problem by distorting the threads further. Tapered pipe threads are not to be used for mechanically joining components in a system where load would be placed perpendicular to the plumbing line. This weight will further weaken the sealing joint. In light of its sealing mechanism, assembly restrictions and design limitations, pipe thread connections are optimal only when the following conditions exist:
1. Minimum hydraulic shocks or vibration
2. The fitting is limited to one or two re-uses
3. The system utilizes low pressure; or few operating cycles (static
condition) for higher pressure service
4. Skilled workers trained in the pros and cons of pipe fitting assembly are present

For these reasons, tapered pipe threaded connections are not recommended for dynamic pressure systems.
So this was the end-result of yesterday's project:


Anyone want to take bets on how long this one will last? Now I'm researching STEEL fittings.
Dave B.
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Last edited by dbarton; 01-08-2010 at 01:05 AM..
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Old 01-07-2010, 09:29 PM   #2
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Looks good Dave - this latest fix definitely looks a lot more stable than any of the earlier pictures.
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Old 01-07-2010, 10:06 PM   #3
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Yeah, looks better but I still wonder what's going on. Did you happen to run a tap through the block hole to chase the threads? And the brass elbows are notorious for losing their bite. You may end up having to use a Time Sert on the block. Your earlier renditions, while looking a bit, um, engineered, wouldn't of themselves leak that quickly IMO. If it leaks again, I guess you could try LocTite but I'm thinking your alternator wacked the sender causing the threads to spread. Also, even though VDO expressly says not to, I use Teflon tape on all my senders. If the threads aren't sharp enough to cut through a couple of turns of tape something's rotten in Gotheburg!
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Old 01-07-2010, 10:33 PM   #4
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Get a Denso alt.

I threaded a 5bar sender directly into my b23f block and I use a 100a Denso alternator and I have no interference problems. I reused the same belts and they worked fine.
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Old 01-07-2010, 11:51 PM   #5
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Dave, your latest 'fix' is the best so far. Why not take it further:

get yourself:
....a couple of Aeroquip 2021-2-4S steel adapters....1/8 NPT to AN4
....some Aeroquip socketless fittings such as FBM1231/FCM1231 and FBM1438/FCM1438
....some high temp socketless hose such as FBV0400/FC332-04
....if you want to have the 'braided' look, some of the FBR1200 overbraid
....or some of the firesleeve overbraid
...and some ABA SS miniclamps size 15

one of the 2021 adapters will thread into the block nicely. The socketless fittings lets you decide how long to make your hose, and install the fittings yourself. And the straight or angled fittings lets you route the hose however you want to. The ABA clamps are what I use as extra insurance on a line that just cannot come apart; even though the Aeroquip socketless hose and fittings really do stay together once assembled.

If you must keep the dual terminal sender way down there by the filter adapter, fine. Separating the dual terminal sender from the block IS a good idea....all that weight vibrating on some brass fittings does not make for a reliable install. [found that out the hard way myself a time or two] But, why not relocate it up near the strut tower? Away from the heat and vibration and road crud.

TF
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Old 01-08-2010, 12:27 AM   #6
crandandall
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You could get a remote filter mount with a 1/8 npt port in it so you can run your sender from there.

Something like this

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Old 01-08-2010, 01:15 AM   #7
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Quote:
Originally Posted by crandandall View Post
You could get a remote filter mount with a 1/8 npt port in it so you can run your sender from there. Something like this.
Now that is a nice suggestion.... Thanks.

Quote:
Originally Posted by towerymt View Post
Get a Denso alt.

I threaded a 5bar sender directly into my b23f block and I use a 100a Denso alternator and I have no interference problems. I reused the same belts and they worked fine.
I appreciate the suggestion, but I've grown close to having an adjustable regulator. Can the Denso put out 14.6v? That's where I general run.
Dave
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Old 01-08-2010, 01:21 AM   #8
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Quote:
Originally Posted by swiftjustice44 View Post
Did you happen to run a tap through the block hole to chase the threads? And the brass elbows are notorious for losing their bite. You may end up having to use a Time Sert on the block.
Yes, this last time I ran a tap in there. I think the threads are ok. It appears it has not leaked unless the fitting cracked or loosened from presumed mega-vibration. I suppose unmodified B21FTs are not the smoothest in terms of balance and harmonic vibration.
Thanks,
Dave B
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Old 01-08-2010, 01:31 AM   #9
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I have nothing against AN fittings, but I was hoping to make this a reliable fix without spending $200. I actually don't care for the shiny braided look... would prefer a black plain hose, but I had some pieces of -6 braided handy and I was a bit concerned about radiant heat on that line in the long run being a bit close to the manifold.
Dave

Quote:
Originally Posted by stealthfti View Post
Dave, your latest 'fix' is the best so far. Why not take it further:

get yourself:
....a couple of Aeroquip 2021-2-4S steel adapters....1/8 NPT to AN4
....some Aeroquip socketless fittings such as FBM1231/FCM1231 and FBM1438/FCM1438
....some high temp socketless hose such as FBV0400/FC332-04
....if you want to have the 'braided' look, some of the FBR1200 overbraid
....or some of the firesleeve overbraid
...and some ABA SS miniclamps size 15

one of the 2021 adapters will thread into the block nicely. The socketless fittings lets you decide how long to make your hose, and install the fittings yourself. And the straight or angled fittings lets you route the hose however you want to. The ABA clamps are what I use as extra insurance on a line that just cannot come apart; even though the Aeroquip socketless hose and fittings really do stay together once assembled.

If you must keep the dual terminal sender way down there by the filter adapter, fine. Separating the dual terminal sender from the block IS a good idea....all that weight vibrating on some brass fittings does not make for a reliable install. [found that out the hard way myself a time or two] But, why not relocate it up near the strut tower? Away from the heat and vibration and road crud.

TF
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Old 01-08-2010, 03:41 AM   #10
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Quote:
Originally Posted by dbarton View Post
I have nothing against AN fittings, but I was hoping to make this a reliable fix without spending $200. I actually don't care for the shiny braided look... would prefer a black plain hose, but I had some pieces of -6 braided handy and I was a bit concerned about radiant heat on that line in the long run being a bit close to the manifold.
Dave
I can understand that. Paying full retail for AN fittings can be a killer. Check out:

www.aeroquip.cc

...their prices online are pretty good. I've been buying from them for some time.

For the radiating heat, some thermotec wrap on #1 runner does a lot to cut down on the heat getting to either the alternator or to the oil sender. Or to the P/S pump and supply hose on a 7/9. Makes a considerable difference.

TF
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Old 01-08-2010, 03:58 AM   #11
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http://www.anplumbing.com/ has comparable pricing. It's also a bit easier to navigate than the Aeroquip website.
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Old 01-08-2010, 04:31 AM   #12
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hard to believe you cant make the original set work. thats the best way to do it. if your going to use a oil line why wouldnt you just use it in line with the oil feed??
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Old 01-08-2010, 11:31 AM   #13
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Another good suggestion.

edit: I guess it should have been pretty obvious to me since I have an AN line feeding the turbo.

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Originally Posted by yamahapro View Post
hard to believe you cant make the original set work. thats the best way to do it. if your going to use a oil line why wouldnt you just use it in line with the oil feed??

Last edited by dbarton; 01-08-2010 at 11:39 AM..
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Old 02-02-2014, 01:06 PM   #14
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Bringing a dead thread back to life!

I've been doing research for my own project. In the midst of an alternator change I never realized most of my installation woes derived from the sender being in the way @##%#!... so with my engine torn apart it's time to move this puppy!

As it turns out the remote oil pressure sender is popular with aircraft. Go figure, they experience a lot of the same issues we complain about: vibration and sensor fatigue. They also seem to be very safety conscious...so I'm liable to trust their methodologies and parts sourcing (summit racing AN fittings for some haha).

Looking around the web I found one of the more popular variations of an engine bay sensor mount that kills two birds with one stone - mounting & grounding the sender:


source

I've also read here and there (with little documentation to back it up) that you might also consider installing a restriction fitting on a sender line to avoid any wild fluctuation in the readings. Not 100% sure I believe this given the sender is already restricted and any wild variations i pressure would likely be blamed on the hose deforming.
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Old 02-02-2014, 01:33 PM   #15
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Proposed parts list... (summit racing bits)

-4AN M to 1/8''NPT M Steel - $3~
-4AN M to 1/8''NPT F Steel - $3~
-4AN hose end - $6~
-4AN hose end - $6~
3ft stainless hose - $15~
hose clamp - $2~
screw - basically free
scrap metal mount - free

Total: $35~
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Old 02-02-2014, 04:31 PM   #16
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I remote mounted mine from the start using black nylon hose and those self crimping brass fittings. The stuff is all on Ebay and cheap. No leaks. This has been running for many years.
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Old 02-02-2014, 06:25 PM   #17
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With the denso alt it generally fits just screwed into the block directly with the Volvo 9.5x925 belts. Simple enough, painless, free.

Those elbow things are a PITA. Hard pipe and a bracket to the block or heater pipe would work I guess. Steel fitting into block to flare fitting, sturdy bracket on block/heater pipe, flared hard line to 1/8 NPT adapter. Inexpensive and easy with a rented flaring tool. Maybe $5-10 or something at an appropriate supply place.

Or collect a pile of used elbows until you get one that fits well *shrug*.
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