Injector Pop Testing Question (Video)
 

Hey all,

I finally got around to building my injector pop tester. I may be using it wrong, so any input would be appreciated! The injector seems to begin "popping" around 400 PSI or so, and loses its pressure.

http://youtu.be/hq5H-C-g8Bs

Thanks!

For one thing, a liquid-filled gauge is not the best option for pressure testing. Its response time is too slow.

I was told to only use the glycerin filled gauge. My spray pattern looks good but the pressures seem off. I may give a non-liquid filled gauge a try also.

Anyone else have experience with pop testing?

I use a glycerine filled gauge. It just dampens the response a bit so you get a more representative reading.

From what I can see it appears to be working as expected. Your popping is more pronounced than what I get, but I think that's just higher flow with yours. Are you popping injectors with new nozzles or just checking your existing injectors as they came out of the car? What are your readings across all injectors?

I did not watch the video but 400psi is too low. Turbo injector opens at 135 bar or 1958psi. Non turbo at 115bar or 1667psi. They are way off or you read it wrong. Cannot see anything wrong with liquid-filled gauges.

I thought you might have meant it was 400 psi low until i watched the video and saw it chatter around 400.

How was the car running? and did you check your 0 to 60 before you pulled them?

Not sure what, exactly, is being "represented." Except that it's not reality.

I suspect that you won't find a professional injector tester that uses a damped pressure gauge.

Can you show me a single, professional-grade injector tester that utilizes a damped gauge? Bosch? Bacharach?

Here we go again. It is wasting my time to response. I thought you are far better poster after a long period of hiatus.

Last time I checked this was a DIY-focused forum. If we all had access to professional-grade tools and instruments, we'd probably be in the business and have access to professional-grade documentation...though I'd argue that the forums are likely even better in many respects.

Regarding pop testers, if I felt I needed accuracy to +/- 1 psi on a pop tester, I'd buy a $5000 digital unit with integral printer, 16" screen and a .5 micron filter assembly and automatic popping and digital recording of each pop in super slo-mo, rather than building one. I can live with a lot less accuracy and bells and whistles and only have $21.47 invested...and you know what? The car runs perfectly, and has for the last 30k miles since I last popped my injectors.

I kind of like my HF tools, too... and my swap meet tools and my Craigs List equipment. And I kind of like making my own tools and solving problems without investing a fortune.

If you want a dry gauge, go for it...

your popping appears to be around 135 bar... I don't know where you are seeing 400psi pop... it's over 1500psi... hard to tell exactly, as the needle is very slow to respond, but it's certainly not 400 psi...

This little unit has a liquid filled gauge:

Caterpillar Cat 1U6661 Pop Injector Tester w Cart Used | eBay

also, the liquid level in the gauge makes it hard to read the pop pressure... but it's sitting stable around 1000 psi... it only pops as you pump it over 1500...

You make a great point!

For future reference, once the eBay ad expires...

http://www.peachparts.com/shopforum/...1&d=1395865033

http://www.peachparts.com/shopforum/...1&d=1395865107

Can you make even the slightest hint of an agrument that would support the selection of a damped gauge for injector testing? The HF and Craigs List distraction isn't terribly persuasive.

Why would you choose a damped gauge for use in a dynamic situation like injector testing?

Uhhhh, because it works... oh, and because the multi-thousand professional Caterpillar units use liquid filled gauges. If it's good enough for Caterpillar, it's good enough for me.

...that is all

If you think using a liquid gauge is not beneficial, just try using a gauge without liquid and let us know what you find. From my understanding the gauge will break, but that's not what this thread is about. There's a guy who has been very helpful that has very good YouTube videos on pop testing and cleaning injectors for the OM617. He told me that my pressure seems to continue to rise even after I've stopped pumping, and he thinks it's a result of going from 1/4" fittings up to 3/8" fittings. I ordered the right fittings and will hopefully have an update tomorrow.

The gauge does seem to be delayed because from what I can see the injectors begin chattering at 400 PSI. Hopefully this is due to the fitting sizes and not a faulty gauge.

Fitting size will have absolutely no effect on pressure. Liquids are non-compressible so the pressure will be the same regardless the line (or fitting) size. If you check the orifice size on the gauge it is going to be a lot smaller than 1/4". If it were to have an effect, you would need to order a gauge with the inlet size the same as the line size (or tank size, if you were checking the pressure of a tank).

Line size does have an effect on flow rates, but I can assure you that the orifice on the nozzle is much, much smaller than the line size going to the injector.

I have been using injector testers with dry gauges for 40 years. Haven't broken one yet. And I have never encountered a manually-operated, professional tester (Bosch, Bacharach, OTC) with a liquid-filled gauge. Nor can I imagine a single characteristic of a manual tester that demands a liquid-filled gauge.

Why would you prefer a slow-to-react gauge on a pop tester?

Who said anything about "demands". I used a liquid filled gauge on my home-made, DIY, el-cheapo bottle-jack-based, perfectly serviceable pop tester because that was what was available and within my budget. I don't need a multi-thousand dollar unit for the once-every-year-or-so-pop-test of my injectors. I'll put the money saved into tools, fuel, gauges or pop corn.

My scale goes way too high too, but for me and the design criteria of the unit I built ...

... it works and it was within budget

Any ideas on why the gauge slowly rises and then ends up falling? I do not see any leaks by the way.

you could have some fluid leaking back into the pump assembly

How might that happen?

Have you ever used a floor jack and had it leak down when the car was on the jack? could also have some cavitation that is settling out but i think that is less likely, also part of the load does go back through the return lines, is there any diesel showing up there? i think it moves that fuel right as injector closes.

Disclaimer: I did not write it
 

Liquid Filled vs. Traditional Gauges

The primary reason for gauge failure is vibration. In traditional dry gauges, delicate links, pivots, and pinions are prone to damage from vibration, leading to inconsistent performance. In a liquid-filled gauge, the fluid fill effectively dampens system pulsation, making the gauge pointer easier to read.

Likewise, humidity and moisture pose problems for dry gauges. Condensation can make a gauge difficult to read or, in some cases, can cause failure due to icing. Liquid-filled gauges, though, are sealed to prevent internal condensation, and by keeping moisture out of the system, gauge movement is protected during icing conditions.

The choice of fill fluid is based on the application, but glycerin is typically used for room-temperature applications and silicone oil is commonly used for extreme temperature applications, especially when icing is a problem. An oil with insulating properties is ideal if the system has exposed electrical contacts.