Hi guys, I have a 2000 7.3, bought it over the summer w/ 165k on it. I put intake, exhaust, and 4 gauges on it. Unfortunately after I bought it it didn't seem to run right, low power and would dog it some times, but no smoke, blow by, or sucking at exhaust. When it started to get cold it wouldn't start. Sometimes it seems like it's only running on one bank and the whole truck shakes on start up. The check engine bulb was conveniently burnt out when i bought it.
I did CCT and it showed #3 and #8...thought it was because of grey CPS. I get a 1316 IDM code. I checked all the glow plugs and they all got red hot when i hook them up to a battery w/ jumper cables. Although one acted funny and the whole thing got hot.

I did a compression test today. The entire R bank checked out pretty good...380-430. The entire L bank was low...the highest I got was cyl #1 at 375psi. cylinder 3 I got 345. #5 and #7 were 270psi...and #5 jumped to 375 after a tablespoon of oil...but #7 only went to 290 after a little oil. I charged batteries and checked and rechecked and L side didn't improve.

So I'm hoping I did something wrong with my compression test, rather than having to replace the engine. If it is just plain old poor compression then ideally I'd like to stick another motor in it in the future. But for the time being I'm going to drive it...I guess I don't really have anything to lose...right? Any thoughts would be appreciated.

 

You likely have a loose UVCH... that triggered the code and will give intermittent running on a bank.

As for the compression - that sounds more like a head gasket, but I'm really not the one to ask on this.

 

Thanks for the reply...I didn't notice any looseness and when I went to do the 50cent mod, the quarter wouldn't fit because it must be an updated harness or whatever that doesn't give that wiggle room like the older ones. But one of the larger wires on the part of the harness that you disconnect outside of the valve covers that powers some of the glowplugs had some plastic missing but wasn't frayed. I wrapped some electrical tape around it for now.

I hope you're right about the head gasket, and I did read that could be the culprit when 2 adjacent cylinders read low.

I'm really surprised there isn't more threads on compression on these powerstroke forums..cuz I'd really like to make sure I'm not missing anything.

 

Also one thing I noticed is that on the entire L bank after cranking...the gauge holds the pressure and barely moves...the R bank would lose pressure slowly, but also had higher PSI

 

Whether the reading holds should be a function of the valve in the gauge, not the cylinders. If the schrader valve in the adapter and/or the check valve at the pressure relief button on the gauge aren't holding air, the gauge reading will drop after you stop cranking. I'd run the test on all cylinders again to confirm the results.

For what it's worth, I had low readings in cylinder 7 also. The engine ran OK, but ended up needing other work. When I ran the numbers to fix everything, it ended up coming out cheaper getting an engine from a salvage yard. If I hadn't gotten a good deal on the salvage engine, that may not have been the case.

 

Good to know about the PSI.

Yeah, if I replace the engine, I would just take one out of another truck or salvage. I might be able to buy my buddy's 99.5 for cheap and stick his engine in mine, and I'd have a parts truck left over.

 

The problem (if you can call it that) is... the compression hangs in there on these engines for a crazy-long time. I ran compression on Stinky at 280K miles and I have 375 PSI dead-cold (lowest was 360 PSI). I read a recent thread where an engine with 60K miles had 380 PSI dead-cold. I don't know where these trucks start when new, but a properly-maintained 7.3L won't offer up a lot of compression threads.

With what you describe, I think your compression gauge should be called into question.

 

That is a great problem to have w/ our trucks!

Well, I think the only problem in this situation is w/ the operator of the gauge because I went back a final time and retested and everything is 390+
And I videotaped each one with my iphone just to make sure.

I think the problem I was having is the tight space w/ the rocker arms...I don't think I was getting a good thread like I thought I was.

So while I have the valve covers off would this be a good opportunity to test anything else? If I do have injector problems w/ the hard starting and the intermittent powerloss I'd like to narrow that down.

Should I install the new glowplugs I bought and test the injectors somehow? I have the blockheater plugged in so it will actually start. Lemme know what you guys think
Thanks
-John

 

Since you have the valve covers off and glow plugs are relatively cheap, now would be the time to change them. Other things to check would be the injector hold down bolt torque, rocker pedestal bolt torque, pull the wiring harness connectors from the valve covers and check for burnt/damaged pins and connectors.

 

Congratulations on the compression! Good numbers.

165K on the engine? Based on all the oil pressure and O-ring threads I've read recently, plus the condition of original O-rings I saw when I pulled sticks to installed new injectors... I'd order up some O-rings from Riffraff Diesel (6 bucks per stick) and just do it. If you go this far, just make sure you read up on clearing the cylinders and get input for proper torqueing of the sticks. Torqueing alone has tripped some people up... where I found the fortitude to do a full-on faceplant.

 

Thanks for the info guys i think i do need to deal with these injectors as they might be the cause of my hard starts.

One thing i thought of was would it make a big difference in numbers because my block heater was plugged in with the compression test?

 

If you pull the sticks for orings, Tugly has some good threads on cleaning and inspecting those injector cups. I did orings last summer, and it ran great for a while, but now I'm having issues and I'm doubting the quality of my work. I simply wiped my cups with a clean rag and solvent, I didn't have a means to polish or really clean them up, to ensure that the orings seal properly.

As soon as I get a chance I'm going to pull everything again, but now I think I have bad cups too. I have oil in fuel (by checking the fuel filter) and a gradual but steady loss of coolant (coolant tank is clean though).

 

Do u think i should get them rebuilt professionally (500 economy build at rosewood diesel) cuz with 160k they might start getting tired? Or i was actually considering upgrading seeing that i have good compression but...that might start a big money trail haha. I would def have to read up on installing those bad boys

 

Oil is nowhere near the cups... you may have a leaking oil cooler.

This depends on your Buck$Zooka ammunition supply, and your willingness to part with it for the sake of your trucking enjoyment. Once you get a taste of powering up, it's hard to say "That's perfect, I don't want any more than that - ever." I didn't stop until I ended up with an 8000-pound tire lathe... but that took some mighty-loud Buck$Zooka loads.

 

Yeah, I would like reliability, better MPGs and a good truck for towing a 5-10k lb trailer when needed.

Question: I put new glowplugs in. Should I just connect the UCVH and try and start it up or is there something else I'm missing before I start?