GregH Posted June 11, 2008 Share Posted June 11, 2008 I've got one that has a lack of high pressure oil when it is hot. Big surprise at 78,000 miles... Except that it will build pressure fast sometimes. And other times it won't build pressure to save it's life. Hot engine (EOT over 190), short soak time (like less than 5 minutes), and the truck will restart with no issues. Longer soak time (10 minutes or more) results in a no start until it cools off. When it will not start, the high pressure system builds to 25psi. That's like .28V from the ICP (!). And sometimes when it won't start, ICP stays on 0psi the whole time (.24V) Do the air check. With such a low ICP, there should be a rather large leak. Nope, just a small trickle of air. Cycling the IPR results in no change in sound. So, I pursue the non-changing nature of the sound when cycling the IPR. Pull the IPR, inspect (no screen debris or damage) and replace. No change in the truck's condition. I've pulled the oil filter and cranked it over both hot and cold. The housing fills at about the same rate, and fills pretty quickly. There was an aftermarket filter setup, but I swapped it for factory stuff while testing. Last point, the oil pressure on the dash will not ever register a pressure until after the engine has started. The whole time I'm winding on the starter watching the ICP hold at 25psi, the dash gauge stays down. Even on a cool engine, and a restart is possible, the gauge will not move until .5s to 1s after the engine has started. When this thing starts, it starts quick. No slowly building ICP. It's like it's all or nothing... Usually high pressure leaks will go to 100-300psi, rather than 25.... Anyway, if anyone's got some insight, I would appreciate it.. Thanks! Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted June 11, 2008 Share Posted June 11, 2008 Usually high pressure leaks will go to 100-300psi, rather than 25.... Anyway, if anyone's got some insight, I would appreciate it.. All I have to offer is speculation - we have all seen a this kind of stuff and the cause usually is something typical that is just acting in an untypical manor... like a STC fitting that has simply unlocked from wear due to flexing over the last 78,000 miles. The seal may still be intact but the branch tube is the only thing keeping it together. I think you know as well as any of us that sometimes you have no choice but to put your water wings on, hold your nose, jump in and start swimming. Quote Link to comment Share on other sites More sharing options...
mchan68 Posted June 12, 2008 Share Posted June 12, 2008 TSB# 08-09-09 Quote Link to comment Share on other sites More sharing options...
Mekanik Posted June 12, 2008 Share Posted June 12, 2008 TSB# 08-09-09 +1 If I had to guess, I would say it probably needs a STC fitting. Possibly a dummy plug o ring, but those usally don't leak as bad as you are describing. Quote Link to comment Share on other sites More sharing options...
DwayneGorniak Posted June 12, 2008 Share Posted June 12, 2008 I just had two like that in the last two days and they were the oil rail plugs with blown out D-rings. The longer they sit shut off, the more oil they drain out of the high pressure rails while the reservoir for the pump stays full. The high pressure pump has the oil still in the reservoir and after you start it, the low pressure pump takes a little while to refill the reservoir because the high pressure pump just sucked it all up to pressure up the rails which also shows low oil pressure on the low side untill the low pressure pump catches up. Keep on the TSB diag. Quote Link to comment Share on other sites More sharing options...
DamageINC Posted June 12, 2008 Share Posted June 12, 2008 There's a nitrile glove in the oil pan intermittently clogging the pickup. Booya! Dave Quote Link to comment Share on other sites More sharing options...
GregH Posted June 13, 2008 Author Share Posted June 13, 2008 Found it - STC fitting. Typical failure that failed in an atypical way. The STC was cocked bigger than shit in the outlet fitting. The o-ring in the outlet was perfectly intact, but the STC fitting and the outlet fitting would not lock together when I had it out on the bench. New style STC, torqued with an old metal bracket, and it's back on the road. Thanks for the help, guys. 'Specially Keith - you nailed it, buddy.. I didn't look into the nitrile glove in the pan hypothesis - sorry inc... Later! Quote Link to comment Share on other sites More sharing options...
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