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Author Topic: CA18ET W/t25 wont spool past Zero, carbon and lots of moisture from tailpipe...  (Read 1306 times)

Offline SpanktheS12monkey

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So here's the issues. I probably already know the answers but I figured I would get a few more opinions.

CA18ET with a T25 Turbo, BOV, Fuel Pressure Regulator, Oil Catch Can

Since I purchased this S12 I have heard a small vacuum leak coming from somewhere behind or under the intake. I have changed out many of the vacuum lines, but not all yet, and still no luck. The vehicle was running fine with this leak, however the turbo was a little on the jumpy side of boost.

I took my S12 on a road trip one day and when I got off the freeway at my destination, the engine sounded as if I had like 4 bad lifters, which is impossible because the CA18ET does not have lifers or push rods, just rockers, valves and springs. On take off the engine ticks really bad after 2000 RPM but Idle sounds fine.  When I got to where I was going I inspected the engine really good and found the Wastegate was stuck in the closed position. I did managed to get it unstuck.

The car did make it home. I didn't really want to drive it, but didn't have much choice. It was a very slow ride home because the turbo wasn't wanting to spool. When I got home and the engine cooled I soaked the Wastegate with PB Blast to help free it up, which worked but the engine is still having issues.

Here is what its doing:

CA18ET idles smooth as silk but...
My turbo gauge shows -20 boost at idle and will not boost past -10 during throttle. When it gets to -10 it drops back to -20.
Past 2000 RPM the engine ticks from the back 2 pistons.
Throttle doesn't always want to work, causing the engine to backfire, spit or sputter around idle.
Turbo makes a god awful ticky noise when it does make boost.
Sometimes it takes 2 cranks on the starter to fire up (this just started happening)
Lots of moisture and carbon spitting out of the exhaust pipe while trying to throttle the engine

Here's what I've done to try and correct it:

Took apart all the intake tubing and inspected it, re-installed it and insured everything was tight. OK
Removed Valve Cover and inspected Cam for flattened lobes or loose hardware. Everything is tight, Cam did seemed scorched but looked like normal wear. OK
Checked Turbo shaft for play or damage, everything seems fine. OK
Checked Dizzy for loose or wrong spark plug wires. OK
Freed up and lubed the Wastegate on the turbo. Seems fine??
Checked and replaced vacuum lines, still a small leak, but it was running fine with an even worse vacuum leak. ??
Unplugged the Thermostat to check for idle bump. OK
Inspected Fuel Pressure Regulator and Fuel Pump for proper function. 22 PSI with accelerated vacuum bump. OK
Inspected TPS and MAP for functionality. OK
Inspected BOV for functionality. OK

My diagnosis is telling me that I have blown the head gasket or cracked the head, which is causing the turbo to act up.

I'm interested to hear any other symptom diagnosis

Post Merge
Yesterday my naturally aspirated brain was thinking displacement and not forced induction.

After some turbo wrench time, its looking like Oil Boil is gumming up the return oil line. The person before me apparently decided that a Garrett T25 Doesn't need its turbo coolant lines and capped them off.

Capping off the turbo coolant lines does make it easier to work on, but does nothing for hot shut downs.  Turbo timers don't really cool the engine bay down unless you have been driving really hard, and all the heat from the engine and exhaust ends up in the turbo baffle, which causes the oil to boil for 10 to 15 minutes after shutdown. This boiled oil turns nasty quick and gums up everything in the vicinity. If your fresh oil change gets dirty right away, your turbo oil drain is clogging up!

This was the problem, but the problem created more problems. Oil Boil crusted to the inside of a turbo and drain tube will cause erratic pressures in your turbo, which puts undue stress on your turban shaft and bearings, causing failure.  Bad shafts will make noise, while bad bearings will blow oil either into the charge or exhaust side depending on which side goes bad first.

If your lucky, and you catch your clogged drain tube early, you may just save your turbo.

For those questioning removing their coolant lines, or deciding to not re-install their coolant lines, I would advise against it. Your Oil/Coolant fed Turbo will run better, longer with them hooked up.
« Last Edit: 06:18:17 AM / 22-Jul-14 by SpanktheS12monkey »

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