Engine/Transmission (1998.5 - 2002) Turbo Spool Awful after Head Work

[alaskax]

Recently upgraded my HX40 to a BD Super B single. I have really tall gearing in my truck after installing 37's with a 3. 54 diff and . 69 transmission OD. The improvement in spool up put a smile on my face, and made my truck more driveable and enjoyable. It took 2 whole seconds off spool time, and put a smile on my face. Funny, after a few days it only would spool to about 35 psi, even with the wastegate disconnected. Otherwise, it still ran really well. Shortly thereafter, put in a water-meth system, then manually tested it during idle, which almost snubbed the engine and blew the head gasket. Sent the head to Scheid, who refurbished the head, and fire-ringed it. Got ARP studs, and had the local shop put it all together. Now, once I get it spooled up, it only gets to low 30's psi like before, but the bigger problem is that IT JUST DOES NOT WANT TO SPOOL AT ALL unless I really get on it for a LONG time. I notice a lot more "stumbling" at low RPM's, but seems OK once the power finally comes up. Problem is, to get the thing to spool, it resists enough to go to EGT redline almost every time. In fact, I can't drive it in OD, as it goes to redline on EGT, and the reason it does is that it just won't spin the turbo and build any boost. Maybe 3-5 psi in that condition, whereas before it would be 10-15 psi cruising in OD at maybe 70 mph. I have to disable OD just to drive my truck.

I'm mostly convinced it's not the turbo itself, but relates to the low-end stumble that's especially noticeable before truck is warmed up. Very different than before.

Sorry for the long post, but hoping there is a "killer tech" out there that might have a suggestion for me. I've made some calls, but nobody even has a suggestion. Yes, I realize there are a lot of possible variables. Scheid did a pop-off test on the injectors when they did their job.

I want to put in a compound turbo system, but not before the truck runs like it did before! Though it's geared really tall at the moment, it WAS working quite nicely with the new turbo.

Seems to me it likely relates to fueling, but I don't know how. Black smoke still pours out, but spooling just won't happen.



Very grateful!

John

 

[Vaughn MacKenzie]

Have you checked everything over to make sure there's no boost leak? Doing something significant like R&Ring a head you could easily overlook a boot clamp that wasn't tightened or properly seated. Also make sure you reconnected all wiring to your sensors especially the MAP sensor.

 

[Gary - K7GLD]

Other than a possible screwup in the mechanical work, it sounds lots more like an electronics control issue to me - ECM/PCM/wiring

 

[Joseph Donnelly]

Check closely for a boost leak. You may have a blown hose, a hose clamp out of position or loose, or the o-ring seal at the turbo compressor outlet may be damaged or missing. If nothing obvious can be found, go to a home supply store and buy plastic pipe pieces to cap the boost system at the turbo hose and at the hose going into the engine air intake horn. Apply air pressure on one end, and then seal it (a tire valve works nicely in the end cap). Monitor pressure using your boost gauge fitted to the other end. It should hold pressure, and not bleed off quickly. If all that is OK, there may be a problem with the air horn gasket or the gasket from the intake plate to the head.

 

[Joe Mc]

Another thing to check - are the exh manifold gaskets leaking? All the bolts are tight. I was having low boost issues and during the process of trouble shooting I noticed #6 top bolt "gone" and soot marks around the manifold to head surfaces. New gaskets and several tightening sequences after heat cool cycles - all's well.

Oh, not to jinx anyone - how's the inter-cooler. You'll find out for sure using Joe's test procedure outlines above. Hope it's something simple, usually is. Keep us posted.

 

[DCreed]

I would pull the charger and inspect the exhaust housing. There may be cracks in the housing or an issue with the "puck" sealing. It may be as simple as the actuator rod loosened itself.

 

[alaskax]

Wow, thanks so much for the great help, I really appreciate it! FINALLY I got the chance to work on the truck a bit, and yes it turned out to be very simple, a boost leak as you guys suspected. In fact exactly what Joe suggested, namely, the compressor output connection with the rubber O-ring. Nothing wrong with the ring, but the shop just failed to mate the connection properly, and when I tried to pressurize, the air flowed out of the connection effortlessly! Fixed that, and MOST of the problem disappeared. Was back up to about 35 psi from 30 psi, and much less time to spool. Then, since I had already disconnected the wastegate actuator on my BD single, I was concerned about the "play" in the valve/lever that the actuator connects to, and I wired it deliberately open, since it seemed like maybe the valve might be partly closing all by itself. This is apparently true, since when I ran it after that, the boost came up fully... about 40 psi and without all the incredible delay I have been having leading to EGT's redlining.

So, the only remaining oddity is that the truck does not fire up right away, even in warm weather, like it has ever since I got it. Seems to need a little pre-heat even at 50 degrees. Figured that was connected with the boost issue, but obviously not! Oh well, the truck is spunky like before, and I'm very grateful it was so simple. Now I think I'm ready for twins…

John

 

[Sticks]

I'd be getting in touch with the shop that did the work. Not sure if O-ringing the head and ARP studs require retorques, I had to do mine 4 times per instructions (READ - 4 heat cool cycles, and re-torque the studs each time).

If you are having a hard start issue all of a sudden I'd be looking at the fuel line connections to make sure your fuel is not bleeding down from a loose connection, and possibly a low compression problem.

Correct valve lash... lots of work involved in a head job, lots of places a little "oops, forgot that one" or "not quite right" can cause big problems like a misaligned intake connection. The shop should have noticed this on the test drive.

 

[alaskax]

Thanks Sticks,

Yes, the shop did do retourques (per the instructions). I think I would like to do it again now that I've been driving it awhile, just to make sure.

I'm interested in your statement about low compression, because it "feels" that way to me. When I start it, the motor spins REALLY fast like it's effortless to spin it, HOWEVER I also just put in new Optima batteries, so I'm not sure if that is causing the full effect. If low compression, that would be from misaligned valves, right? I really need to check that out, but I'm a bit concerned about doing it correctly myself. I would like to find a very clear procedure so I know I'm doing it right... ???

Not confident at all in the workmanship of the shop on this job. The mechanic DID test it out afterward, and did not see any issue. In fact, my confidence in him plumetted when I found myself arguing with him that anything is wrong with it. That kind of defensiveness has no place with my truck, money, and time!

 

[Sticks]

Tools, time, and ability. If you have never been that deep into an engine, then I would recommend finding another shop to check into it.



Checking the valves to see if they are over tight is not that hard. Remove the valve cover and the crank case breather adapter (on the timing cover in front of the VP44). On the VP44 drive gear there will be an indicator hash mark. Rotate the engine around using a 24mm (IIRC) socket and wrench while using an inspection mirror to watch the hash mark. Once it gets to either 12 O'clock or 6'oclock, then you check the rocker arms for movement.



12:00 = intake and exhaust on cyl # 1, then intake on 2, exhaust on 3, in on 4 and ex on 5. Rotate the engine to 6:00, then check ex on 2, in on 3, ex on 4, in on 5 and both on 6. If the rocker arms have some movement (READ - you can rock them back and forth and feel a slight tap) then over tight valves are not your issue. Specs are . 010 (+/- . 005) for the intake and . 020 (+/- . 005) for the exhaust between the rocker arm and the valve bridge.



If you are interested in taking this on yourself, I strongly recommend getting an OEM factory service manual (NOT HAYNES) for your truck.

 

[alaskax]

I've adjusted valves in my past life, but not on the Cummins. I want to do it. Was going to some time ago, but could not get the breather adaptor off. I'm sure that can't be TOO hard to overcome!

Thanks for all the specs! I have a OEM factory manual I got years ago, so I just need to spend the time to make sure I'm doing it right. Thanks for the great help!

When retorquing the head, is it important to loosen the nuts first? I'm assuming yes. I assume you go in the in suggested order, loosening a nut, torquing to 125 ft-lbs, then on to the next one... ??

 

[Sticks]

I've adjusted valves in my past life, but not on the Cummins. I want to do it. Was going to some time ago, but could not get the breather adaptor off. I'm sure that can't be TOO hard to overcome!

Thanks for all the specs! I have a OEM factory manual I got years ago, so I just need to spend the time to make sure I'm doing it right. Thanks for the great help!

When retorquing the head, is it important to loosen the nuts first? I'm assuming yes. I assume you go in the in suggested order, loosening a nut, torquing to 125 ft-lbs, then on to the next one... ??

If you have a service manual, then follow the instructions to the letter (caveat - go with the ARP recommended TQ numbers). The only shortcut or trick in re-torqueing is that you only have to remove the exhaust rocker assembly, and be very careful that the push rods are in their sockets upon install. Valve cover, breather housing and intake horn is all you will need to remove (even then you can get by leaving the intake horn on, but it does give you more room).



Use a pair of oil filter pliers to get the breather housing off (unscrews). Also be mindful of the firewall insulation when removing the valve cover and working on the back 2 cylinders.

 

[Joe Mc]

Also be mindful of the firewall insulation when removing the valve cover and working on the back 2 cylinders.

Cover the back of the valve cover with a towel, make sure the towel drapes down the back of the engine so when you start removing the v-cover the dust from the insulation falls on the towel versus into the head



I remove the FW insulation because its such a PIA and it started to deteriorate any way.

 

[alaskax]

Thanks again for all the inputs!

 

[alaskax]

Well, I followed the factory procudure and adjusted the valves today. Wow, not a single one was within spec on the intake or exhaust side. They were ALL too tight, and most of the inputs had zero clearance. After it was done, I just barely hit the starter and it fired up, just like it used to! And, it runs like a champ! Sure am glad, and at least now I know where I won't take the truck anymore for engine work.

Thanks again for the fantastic help guys!

John

 

[Sticks]

Well, I followed the factory procudure and adjusted the valves today. Wow, not a single one was within spec on the intake or exhaust side. They were ALL too tight, and most of the inputs had zero clearance. After it was done, I just barely hit the starter and it fired up, just like it used to! And, it runs like a champ! Sure am glad, and at least now I know where I won't take the truck anymore for engine work.

Thanks again for the fantastic help guys!

John

Glad you were able to get her running.



Now it is definitely time to contact the shop and find out exactly how much they torqued the studs to, and how many re-torques they did. Heat/Cool cycles can cause the studs to stretch, which would close the clearance at the valves, hence the re-torques.



I would not make an issue of the valve clearance, that problem has been resolved as well as them getting further business from you.

 

[Joe Mc]

Unbelievable . . . :-{} #@$%!