I got my exhaust fixed on the 450 and now need to do the bubble test to decide whether I keep this truck, i.e. fix the A/C so I can actually drive it. I remember having to hunt down the rubber stopper with a hole last time and that place may still be open. If not, can I use a coolant system test kit to fashion the same capability? They already have the cap that seals up the degas bottle with a male Milton fitting in the top. Seems like I'd just push a plastic hose onto that fitting.

AutoZone loans out the kit (pay for it and get your money back at return), and IIRC, the one I got even had a plastic hose. This was it: https://www.autozone.com/test-scan-a...it/1053958_0_0

Would I even need the hose? Couldn't I just plug that gauge into the Milton and watch to see how the pressure changes?

 

Will this even work on my truck with the EGR blocked off at both ends? Those tests are about whether it's EGR or gaskets. What's a test for gaskets by themselves?

 

Watch Hartwig's video on the subject. The test covers both situations. With the cooler blocked, it's going to be a test for head gaskets only.

 

We all don´t want to see this (bubble test at the end of video):



I advised the owner not to drive the truck any further.
Unfortunately, he did not follow the well-intentioned advice.

A few weeks ago I got the truck back with a stuck engine (hydrologged on 2 cylinders).

 

Thanks, Jack. I found a vid here, and from it found his YouTube page with others. LOL, he doesn't talk, which I understand, but I'm not sure what he's doing and what he's looking at in the vids I saw.

Since my EGR is blocked, does the VGT affect bubbles? One vid from someone said the VGT releases pressure into the EGR, or not, and makes the bubbles go faster or slower. With no EGR, does disconnecting the VGT do that?

Watching vids, sometimes there's no bubbles. What is the bubble situation supposed to be with good gaskets and no EGR? Maybe no bubbles at all?

For the record, I'm getting no smoke at all. And I have never seen signs of coolant from the degas - does the red ELC still show white when leaking? I thought my delta was high for a new oil cooler the only time I'm driven it up to WOT, but come to find out I was losing an injector at the time from a loose FICM connector. That prolly makes the engine run hotter in this weather. I'm going to drive it tonight after it cools off and see if that changed,

Maybe, rather than mess with the bubble test, I just need to check my coolant pressure before and after getting up to WOT and releasing pressure from the degas. Would that coolant test kit from AutoZone work for that, just using their cap and gauge, not pumping it at all? I see others in the vids adding a T to the smaller degas hose for their gauge.

 

Believe me, you do not want to hear me speak in your language :-))

Make a T-piece in the small hose that goes from the degas bottle to the radiator. Connect a pressure gauge to it (0-20psi).
Warm up the engine and release the pressure from the degas bottle. Run the truck several times with WOT (preferably under load so that it builds up boost pressure).

This is "the moment of truth"

 

OK, I watched that vid. It looks like he drove it to WOT, and the pressure would build up to 15psi or so as he accelerates. Then, he lets the pressure off the cap and...it seems to do that same thing, right? Which means the gaskets are bad, right? Then, he switches to the bubble test. It's bubbling a little, and when he puts load on it (in another vid he puts it in reverse/foot on brake), it kinda quits bubbling, but when he lets off the pedal, he gets a big bubble.

So, if I understand correctly, if the gaskets are good, and with a blocked EGR, it'll should never build to 15psi. And, after letting off the pressure it does build getting up to WOT, and tightening the cap again, it should never build pressure, or certainly not 15psi.

As for the bubble test, if the gaskets are good, blocked EGR, WOT, should there be no bubbles? Or just a small steady stream that doesn't increase under load? Does disconnecting the VGT do anything to the bubbles with a blocked EGr?

 

After venting the pressure and driving it again, you will still build some pressure. It should be quite a bit below the 15 psi though.

 

OK, thanks, guys. The store with the rubber stopper isn't open today, so I'm going to check out the AutoZone kit. Or go but a gauge at Harbor Freight. Try to do this tonight.

 

Well, that was encouraging, but I'm not convinced. I got the coolant pressure test kit from AutoZone. Last time I used it on the bus, I had trouble getting the cap to seal, and same this time. I was testing the seal by trying to pump up pressure in the truck, as the tool is designed to do. I couldn't get it to move the needle, so I switched over to the universal rubber plug adapter provided. It expands in the hole like those replacement freeze plugs they sell. With that, I was able to hand pump a few pounds of pressure into the system, and it didn't seem to leak out.

So, I started the truck, leaving those few pounds I'd pumped in the system. I had cars behind me in the driveway, so I just idled there. It was in the 180s when I decided to rev the engine to hurry the thermostat. Kept my foot on the brake and put it in reverse while revving for less than a minute, maybe 1500-2000 rpm. Jumped out to look at the gauge and it really hadn't moved. However, I moved it too much and it blew the stopper out of the hole.

No biggie, I was almost ready to let the pressure off anyway. So, I got the stopper back in and let it Idle a little bit more. When I next checked, the EOT/ECT temps had flipped, so I figured the TS opened up and jumped back it to put some load on it. Foot on brake in reverse, I revved it for another minute. Checked, nothing, revved it some more. Finally got it to register 3-4psi, but that seemed like as far as it was going.

I'm just not sure that stopper was sealed good. Not sure what the gauge and T fittings cost, Harbor Freight closed early tonight before I got there. I'll try again tomorrow and actually get it out on the street.

Other note - I never really saw the boost gauge on my dash moving while revving with foot on brake, and forget which two PIDs calculate that. IIRC, there are multiple MAP PIDs and I couldn't tell which was which. Not getting any codes on the truck with TP and FS.

 

Stupid question: is there any difference between a fuel pressure gauge and a coolant pressure gauge? Both measure fluid pressure. I need a fuel gauge too. If I bought a 0-100psi gauge, could I tee it up to check coolant pressure, then change fittings and use it as a fuel gauge. Maybe it needs to be 0-30psi for the coolant to be more accurate? I'm thinking the coolant test is a one-time, yes or no, decision.

 

The internal "soft goods" are most likely different and may not be compatible with another fluid.

 

Hmm, that sounds like I need to actually get a gauge made for coolant. I see gauges that claim to be for "water, oil, and gas." And there is one that says coolant at NAPA. Thanks. I imagine there are quality differences - I see prices from $5 to $80. And some are stylish for permanent installations, I suppose.

 

Well, I didn't make it far today. I bought a gauge and fitting to tee into the coolant although when I did my driving test, one fitting had a small seeping leak, and I'm not sure if my readings were accurate. And, I've now lost my boost again - I'm getting 2262 and 0299 codes. I think that might be a leak at the downpipe/turbo connection. That connection got wiggled a whole lot when I was installing the new cat-to-muffler pipe and needed to rotate the rubber hanger grommets for everything to line up. So, again, with only a few pounds of boost generated, I'm not sure that my pressure test data is accurate.

That said, I did get the truck up to WOT, the thermostat opened, but I never saw over 5psi of pressure. Thinking about all the threads I've read on this issue, I can't recall any saying what the pressure should be when everything is fine. Does 5psi sound whack, or is that normal?

Question: while trying to generate boost by revving the engine with it in reverse, after a minute, I saw wispy black smoke coming from under the hood, right over the turbo/downpipe area. Would that be an indication of that bad pipe connection, or is it coming from the turbo itself? I've never actually had this turbo work properly yet, that I can confirm. The other time I drove, I didn't have that exhaust connected and everything was so loud, I couldn't tell. Again, these big trucks and my buses don't drive/perform like 250s. The difference between running good and bad is not as easy to distinguish - these big trucks just drive slow and strain all the time. Maybe wispy black smoke is normal when forcing the engine like that, IDK.

Here's a twist - I also get a P0500 code now. I'm going to clear it and see if it comes back on the next test. On this drive, I had to push the pedal to the floor hard to finally get a downshift (not sure of the gears, driving ~35mph city street). Felt like it downshifted two or three gears, maybe from 6th to 3rd. It'd jump to 3000rpm and scream (not sure if there was boost, happened too fast, I forgot to look). This big heavy truck doesn't like the bumpy city streets and my headache rack is still broke, so I'd back off as soon as it downshifted like that. I wanted to get some happy middle gear, but no luck.

Apologies, I didn't expect all these boost issues, I had no codes idling in the driveway when I took off, and wasn't prepared to monitor or test all this other stuff. I'm wondering if the P0500 triggered because of that aggressive driving and downshifting. Note - this truck hadn't been driven for several years, and has only made one drive over a few miles since I've started working on it. And, I've disconnected the batteries for several days since that trip. I'm wondering if the tranny just needs to relearn and the lack of boost is messing with that process combined with my crazy driving to set that code. I didn't know the code had set and didn't look at the speedo while I was driving. Maybe since the code hadn't actually triggered a CEL, it didn't affect the speedo.

So, anyway, I'm thinking I'll focus on the turbo issue first and see what happens with the P0500.

I'm hoping that low pressure wasn't a fluke. I still have no reason to suspect gaskets, just want to be sure before spending more money on this.