Finally found my leak, now need to fix it

For some time I had a small oil leak on my engine and was not able to find it ( maybe it was too obvious). This morning on my way to my anchor spot I finally found it.

The leak is on the T fitting on the engine block where my 2 oil pressure sender are connected.
On the picture below it is the red T on the block and the leak is at the connection on the engine block


Now I need to fix this and I am thinking either to use teflon tape on the fitting thread or some kind of liquid seal.

Any advice?

L

Teflon tape should be good if i recall msds says up to 500 degrees Fahrenheit. I never liked the ptfe goop when i used it for propane fittings.

You could try RectorSeal #5 or 7. You can buy at most of the box stores.

RectorSeal® No. 5® Number 5 - RectorSeal

Larry M said:

You could try RectorSeal #5 or 7. You can buy at most of the box stores.

RectorSeal® No. 5® Number 5 - RectorSeal

Click to expand...

Sounds a bit like PreparationH - does the same thing I guess - seals holes

Just interested: why do you have 2 x oil pressure senders there? or is one a switch?

Thank you TowLou was wondering if teflon was sustaining high temps.

Thank you Larry will take a look at this one.

Lol @ BrisyBoy, not sure prepH would do the trick !

Aquabelle, I have two senders, one for the flybridge gauge and one for lower helm gauge.

L

Lou....you probably know you can get a "2 station" single sender that will do that for you (send correct electrical signal to 2 x gauges).

oil leak

It is my understanding that you should never use Teflon tape on oil fittings. Fragments may break off and clog small passages.

Ian

Aquabelle said:

Lou....you probably know you can get a "2 station" single sender that will do that for you (send correct electrical signal to 2 x gauges).

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Yup but I prefer to have separate senders so if one fails I still have another reading. Allow to check if the issue is the sender or the oil pressure

L

I would use Permatex thread sealant on tapered threaded fittings.

Permatex and Rectorseal are good sealants for this application. Also Loctite makes two good thread sealants for oil/hydraulic use, not as a locker.

I do not use TFE tape anymore on oil or fuel systems. Used to do some Hydraulic work and TFE tape was verboten at the risk of the job. Not worth it. Not only that but bits of tape could and did cause very difficult to track problems.

Years ago I did use tfe tape on a NEW gear oil pressure sensor and when tested had no pressure. Darn, removed the sensor thinking it was faulty. Nope, a wee bit of the tape had covered the hole and blocked the oil. Faulty workmanship sure but still not worth the trouble. Cleaned it up and all was well. Used a sealant.

I do use tfe tape but the yellow gas rated stuff on water and such fittings.

As many state Teflon tape has it's problems BUT 99% of them are operator issues when applying the tape here's how it should be Done

1) Pay attention and never let the tape cover the end hole (or even close it it)

2)When wrapping Teflon tape around the male edge of the pipe/fitting it is important to wrap the tape in a clockwise direction. To do this hold the pipe in your left hand, or have the pipe/fitting to your left side if it is a mounted pipe/fitting. Put the tape on the threads and run the tape around the threads BUT NOT over the top of the fitting.

3)Depending on the density of the tape, you may wrap the tape two to three times ONLY. If you have a thicker (4 mil) density then two wraps should be adequate. However, if you are using a 2 mil or less density tape, then at least three wraps will ensure that the seal is sound.

4)Make sure that the tape wrap is tight enough to adhere to the shape of the threads. When you attach the two sides of the pipe make sure that no tape has overlapped on the open end of the pipe.

Cheers Steve

I would use permatex number 2.

I would try tightening it.

Yep, try tightening first. Tapered threads seal themselves mostly, without needing any goo.

You really should have an oil pressure alarm switch, a functioning alarm system is better than watching gauges.

One of the reason tapered threads leak is due to over tightening which will damage the threads. These threads should be tightened until they do not leak and a very little more.

I would be concerned that you have 2 sending units hanging off the second of two T's. You try to set up your sending units so that you have only one t there.

Ken

That is a lot of mass sticking out the side of a vibrating diesel. See if there is any way to reduce the mass or shorten the shorten the lever arm. Perhaps a different fitting that mounts the big duced vertically instead of sticking out.

Rector seal is what I use and while NPT fittings are tapered to seal themselves once used they don't seal as well. You will probably need a new fitting at the block so that when tight is will line up with that tube.

Ski in NC said:

Yep, try tightening first. Tapered threads seal themselves mostly, without needing any goo.

You really should have an oil pressure alarm switch, a functioning alarm system is better than watching gauges.

Click to expand...

I will try to tight it but I will need to be able to add a full turn as the line going out (red one on the pic) is a solid pipe that I will need to keep in the same position.

So you would recommend me to have a single sender dual station plus an alarm in place of two senders single station?

L

I did not thank all of you individually but you can all receive my gratitude for your help

L

"That is a lot of mass sticking out the side of a vibrating diesel."

Perhaps not using brass fittings would be more robust?

Found this product from permatex, looks like it is done for this usage:
https://www.princessauto.com/en/detail/high-temperature-thread-sealant/A-p6400048e

I am not sure the fitting on the engine block is brass, as it is painted I do not see the bare metal. The other T where the 2 senders are is brass indeed. For now it is not leaking on that brass fitting but in case that happens, are these type of fitting existing in something more robust?

I may have some other place on the bloc where I can connect senders etc but I will have to find as it is an old undocumented engine. As an example I would like to add an oil temp sender but for now I did not find where I could connect it.

L

One thing of importance is these tapered threads are designed not to have teflon etc, it spoils the electrical connection ( ground ). And stops the senders working properly.

Take it appart clean and exmine the threads and reassemble with a little light oil on the threads.

Martin J said:

One thing of importance is these tapered threads are designed not to have teflon etc, it spoils the electrical connection ( ground ). And stops the senders working properly.

Take it appart clean and exmine the threads and reassemble with a little light oil on the threads.

Click to expand...

Indeed this was my main concern of using any sealant. Does anybody know if the sealant from permatex would allow ground connection or isolate the thread? In other words is it conductor or not?

L.

Both Teflon tape and Permatex used as per directions (IE: SPARINGLY) will not cause isolation issues, once these taper threads start to bind ON EACH OTHER it's metal to metal , it will cut through Teflon tape like butter or Permatex , they are designed that way (interference taper fit) the Teflon or Permatex fills any voids or miss alignment/imperfections in the threads and there fore seals at that point only,every where else it's squeezed out of the contact area

Again back to my earlier post (In experienced Operator Technique 99.9% of the issue) if your at all worried check with a multi meter prior to completion,

As a class commercial maritime chief engineer i have fitted thousands of oil water/ fuel /LPG/tapered single wire fittings/senders/alarms over the past 40 years and have never once fitted "DRY" and never will like wise I have never had to redo a single installation due to no electrical connection

Cheers Steve

Unless the fitting has turned, it is strange that the threads would start to leak. I suspect there might be a crack in the fitting. You'll figure that out when you unscrew it.

A little thread drift. I once had an oil pressure sender try to kill me. I was sitting on the ramp at Fort Lauderdale International in my Cessna 172. The engine was running while I listened to the recorded airport info on the radio. A guy came running up and banged on the airplane. I shut down the engine so I could talk to him. He told me I had a big puddle of oil under the plane.

Turns out the diaphragm in the oil sender had failed and the engine had pumped all the oil overboard.

I'm really glad it happened on the ground. Ten minutes later I would have been in the air.

Update!Temperature Sensors & Switch

As I mentioned earlier many sender unit manufacturers require no sealant for efficient grounding. Below I have copied VDO's recommnedation.

https://www.vdo-gauges.com/sensors/temperature-sensors-switch.html


Using the expertise we’ve gained in developing specialized solutions for many of the world’s leading manufacturers, we offer a large portfolio of pressure and temperature sensors that we manufacture our sensors in our own ISO and TSO registered facilities, using the same quality materials, engineering processes, and quality standards as our OE products. Our sensor range includes pressure sensors and switches and speed, RPM and rotational sensors and position sensors as well as temperature sensors and switches.

Note: All Temperature sensors are designed to work with VDO gauges only. Sensors are matched to gauges according to maximum reading on dial face. All sensors are standard ground (sensor case to common ground). Please note: VDO sensors have tapered threads and DO NOT require the use of Teflon tape or pipe sealant. This will interfere with grounding causing incorrect instrument readings.

Temperature Switch Technical Specifications:

Switching Capacity: 1.2W to 3W, non-inductive for monitoring various mediums
Normally Open, Single Circuit, Standard Ground Systems
Rated Voltage: 6V to 24V
Type of Contact: SS = contact closes as temperature rises
Break Point: 5o C max. below make point
Contacting Mode: Slow-acting

I'm with Steve53 on this one. The bad surprise is when the block cracks due to overtorque trying to stop a hot oil leak. Permatex PST is what i use and this electrical fear is unfounded.
btw, many of my Asian customers have heartburn with tapered threads on industrial equip. We cant give a definitive torque value. Installers like straight threads with a o ring. But i digress.

Martin I am not trying to go against VDO engineers but I'm positive even they will tell you that it is in perfect new conditions using mating VDO taper
to VDO components they normally seal,

That said even most brand new engine's come with with these fittings sealed with products such a Loctite/Permatex or similar as we all know it's not a perfect clean world out there,

Also how many yachties/boaties know what there engine uses in the block for the threads LET ALONE OTHER TEE'S ETC AS USED ON THIS ENGINE: it could be BSP straight/BSPT-Taper
There are parallel and tapered pipe threads for all pipe standards. NPS, National Pipe Straight, is the American only standard for parallel or straight pipe threads, Any BSP thread will not seal ("WITH OUT SEALANT"with the NPT as the thread pitch is different 55 degrees as against 60 degrees

From the Engineers Handbook Quote:Tapered pipe threads need a sealant for leak-free connections. It fills any voids between the two threads that could cause a spiral leak. They also function as lubricants between the male and female threads.

This is not NPTF. NPTF stands for National Pipe Taper Fuel. It is also called Dryseal American National Standard Taper Pipe Thread. The design of NPTF only provides leak-free connections without using sealants.

With all the unknown issues USUALLY ENCOUNTERED as above i will gladly stay with my 40 years hands on experience "with no issues" and continue to use sealant than take the risk,

Clients dont like it when you have to remove an engine due to accessibility issues with a leaking fitting!!

Cheers Steve