Engine/Transmission (1994 - 1998) Valves Adjusted, Strange Results

[MMcCallie]

Hadn't had my valves adjusted in roughly 50,000-60,000 miles and was talking to my mechanic about it and he suggested they be adjusted every 10,000 miles. I was telling him how I'm making about 10 psi less boost than a year ago and my fuel economy has dropped a few mpg.



I've heard lots of different numbers as to when they should need adjusting but he said the engine should purr at an idle perfectly smooth, like it used to but no longer does and that convinced me. So he adjusted the valves and told me both the intake and exhaust valves were all quit a bit off and were badly in need of adjusting.



Took it for a test drive and am making even less boost, max of 35. 9 psi at about 100 mph up a mountain, EGTs just under 1,700 F. Previously seeing 36. 7 psi with EGTs reading over 1,900 degrees. I wonder if my BD X-Monitor is inaccurate. Anyway, still lots of smoke even at max boost.



Strangely, boost decreased the more I drove. Boost was also far slower to respond and climb. Between stop lights I was no longer seeing any boost, even up to 45 mph unless laying very heavily into the throttle, even then only in the teens but tons of smoke. Another thing I noticed was that the engine does seem to be smoother and sounded different under heavy throttle. No longer as pingy, more of a deep, mellow roar like a V8.



Mechanic had waited until the engine was cool to adjust. Says he set everything by the book. since the engine runs smoother, I assume he's right. He's suggesting a boost leak since I've had low boost for a while. Last fuel filter swapped a month ago was filthy so we'll swap that out too.



Is it possible for the engine to make more smoke and less boost after a valve adjustment? Engine still seems so responsive so I don't suspect the timing has slipped but we can check that. He said we'll isolate the boost tubes and the intercooler from the turbo and check for leaks.



If I still have low boost after we figure things out, how do we adjust the wastegate actuator rod on an HTT HTB 62/12 for more boost? Can't even see it from above.



Thanks for any ideas,

Matt

 

[SRath]

My '96s passenger side rubber boot connecting from the turbo to the intercooler lays hard up against the relatively sharp edge of the frame rail. If I ever develop a boost leak, that is where I'll look first, despite padding it.

 

[hsmith]

If those egt's are accurate, you will soon have more serious issues to be concerned with.

 

[JacobsD]

sounds like your wastegate could be sticking slightly open.



Ether way, sounds like you need more air or water/meth, IMO.

 

[jakprince]

He didnt get the valves mixed up did he?Maybe set the exhaust to the intake specs and the intake to the exhaust specs?

 

[GAmes]

Every 10,000 is way too often. I do mine at 50k and then any adjustment is minimal, and usually only two or three valves. I'm thinking he screwed it up. He is definitely looking to make money from unnecessary work.

 

[Flinty]

I think the manual calls for every 20k. I adjusted mine for the first time at 145k, four valves needed adjustment by about two thousandths, pretty minimal IMO. Maybe a second opinion is in order. I agree any egts over 12-13 hundred is pretty risky. I've read stories of fellas pushing 1600 for just a moment and ending up with some really expensive scrap metal. Maybe your right and the pyro is on the fritz. (hopefully).

 

[surfbeetle]

If I remember correctly, it was around 20k for the first adjustment and then every 40k thereafter. I do mine just once per year and all is well, but keep in mind that for me that's about every 9 to 12 thousand miles.



I think that temperature extremes as well as total miles have an effect on valve lash. So I would rather adjust them too often than not enough.

 

[MMcCallie]

Mechanic said the intake valves were within a couple thousandths but the exhaust valves were as much as ten thousandths out. Runs smoother now. My truck has definitely seen temperature extremes down to 50 below and well over 100 in the summer. It has also seen a great deal off rough off road action rock crawling. 4kgsk as well.

It turned out that I had a boost leak. When the mechanic adjusted the valves he'd accidentally pulled apart a fitting connecting a couple small hoses I have running to my gauge and water/meth controller. I still wasn't making any more than 35. 9 psi so he told me he knew a bunch of guys who had pinched off the wastegate line going from the compressor to the exhaust side of the turbo. So he used a zip tie and pinched it off. Truck is now easily reaching 44 psi and has cleaned up the smoke drastically. Running much better. Seems like the wastegate may have been starting to open around 20 something psi because it pulls much harder now.

EGTs still reading over 1,500 but I really don't trust my X-Monitor. I'm on it's second thermocouple and BD wants me to pay to have them test and possibly fix the gauge. Fuel filter was also only a month or so old but the orange coloring had gone gray, not just from dampness, and there were small particles in the fuel. I'm thinking the fuel filter was part of it. Turbo seems to light quicker now, like around 7 psi instead of until 10 so the truck is now running noticeable better.