I'm hoping somone here can help me with this issue. I just want to make sure I am getting everything right.

Over the last 500 miles since I bought the truck, a 2001 1500 5.2l 4x4, it has lost a little bit of coolant. The level in the reservoir has gone down about 2 inches. I have also burned a quart of oil, I know the plenum is bad (I can see oil on the plate looking through the throttle body and I did the vacuum test anyways). I have an aluminum plate, gasket and bolts coming in the mail as I type this. There doesn't seem to be oil and coolant mixed. The previous owner said he usually gets 235-250 miles per tank, I get 180-195, about 9 MPG... The truck seems a bit down on power compared to my 1500 5.9l 2wd, but that truck also has tow package and smaller tires, and 2 friends have 5.9L R/T Dakota's which are lighter and again have the larger 5.9L motor. When first started there is a slight puff of blue smoke, and then white after that for about a minute or two, like when starting up on a very moist morning after a wet night. It won't smoke again until completely cool. When I bought it a month ago the throttle body had quite a bit of carbon deposited all over it (mostly on the passenger side) from what I would assume is backfiring (or could it be from oil burning off or evaporating from the plenum plate and depositing after the engine is shut off?), but I have not heard it backfire under different loads, hot or cold, and revving the engine with the air filter off I do not see any backfires through the TB.

Compression test turned up the following (done 3 times):
150,115,100,130 on the drivers side 1,3,5,7
120,125,125,125 on the passenger side.

To me this seems like an obvious head gasket issue with #3 and #5 being down. Hot or cold, the numbers were always +/- 5psi compared to the above. I was not able to do a wet test yet because I don't have an oil squirter or funnel that will reach that far through the plug shrouds on this engine (not sure what to call them). I know a wet test will help determine if the rings are bad, I will do that ASAP. 1 being that high seems a bit odd to me. Hot it went 150, 155, 150, cold was 145, 145, 150. I was under the impression this is a 9.1:1 compression engine so I was expecting around 130-135, maybe 140psi. Could this be stuck valves? After 112k miles of being worked (towing a several thousand pound boat a few times a year, and plowing 4 driveways the last 4 or 5 years) I thought getting 120-130psi and being within 5psi of each other was good.

Plugs 2-8 look like the engine is running hot or lean. Like #22 or 23 here: http://www.dansmc.com/spark_plugs/sp...s_catalog.html. Also 2,3,4,5 were a bit wet with oil near the threads of those cylinders; 5 being the worst, 3 was better, 4 and 6 barely had any wet deposits. These wet deposits were only on one side of the end of the threads. I would have to guess this is probably from the plenum issue though. #1 looks normal.



Should I spend the extra money for the 'Severe Duty' head gasket ($30-40 vs $15 each from http://www.rockauto.com or NAPA)? The truck will be used for home remodeling/light construction-hauling several hundred pounds in the bed to a couple thousand pound trailer, and plowing in the winter. Should I also do the timing chain+water pump while I'm already at tearing part of the engine apart? A few people seem to think the blue smoke at startup is the valve seals, should I bother doing these? Or is it most likely the plenum? Valve seals are cheap, are they easy to do?

 

That smoke at startup sounds to me like valve stem seals, maybe guides, too. It'd be wise to check the guides while the heads are off. The seals are easy enough to do. I wouldn't suspect the plenum as being at fault for the startup smoke, since the oil that collects on the pan doesn't have any way to get into the cylinders after shutdown.

Were it mine, I'd do the timing set and water pump at the same time, and at least the bypass hose whether it needs it or not. And whether or not that's done, I'd get a new cat and pre-cat oxygen sensor installed, since they're certainly suffering from the oil being thrown at them.

 

It just passed emissions. Readiness passes within a couple days the times I have had the battery disconnected on the truck. I'll have to borrow a gauge to check if the exhaust is flowing correctly. I've done that once before on my car when the cat clogged. O2 sensors were replaced at 105k miles exactly year ago.

I did not see any records about the exhaust. I had pulled both the o2 sensors recently because of the bad gas mileage I had been getting and they had quite a bit of carbon on them, which was pretty much expected. Even more than when my car was running rich before it was tuned properly (air fuel of 11.5:1 under boost, 12.5-13.5:1 under normal driving, turned out to be a bad MAP and MAF sensors playing off each other).

Also, at 105k the TB was cleaned, but at that point it probably would have needed it anyway. The was one service a few years ago about a CEL and diagnostics test drive about it not running right, but other than that I don't see anything odd. According to the owner everything was serviced by this one garage all the records are from. Also it never needed more than a quart or two between oil changes, but that was only the last year or two at the most.

 

Fix the plenum. That should be the first priority. The list that Unreg rattled off is a REALLY good idea. Especially if none of it has been dealt with recently.

These heads are famous for cracking between the valve seats. Do a cylinder leakdown test if you can. That may tell the story right there.

Puff of blue at startup is indeed valve seals. Not a bad job, just tedious.

White smoke that stops is more than like moisture condensing in the engine/exhaust. Coolant leaks are also something these engines seem to have a lot of. Check freeze plugs, especially those behind motor mounts.... bypass hose. (which you can't even see, unless you take the a/c, and alt bracket off), and timing cover. (both pump to cover, and cover to block)

 

On the coolant, also try burping the system. If there is no loss visible, it may have air in there that is starting to work out, causing level to lower. More likely a leak at tstat housing or timing cover, but you never know. These leaks are not always visible and often do not drip to the ground. It just cruds up on engine.

If O2 sensors have oil on them, you can bet the internals of the cat do as well. May want to plan on changing that out before it plugs solid.

Good sticky thread on here related to plenum. And certainly do as recommended on timing set (double roller chain), tstat, and water pump. You don't want to be onthe side of the road. Making a living in remodel work is tough enough without having a truck down!

I also did plugs, wires, rotor and cap when I did mine. Also, the heat shields around the plugs can be just pulled out with a pair of channel locks. Pull straight and slight twist. They just push back into place afterwards. There is a TSB on routing plug wires to eliminate misfires. You may want to do this while you have it down.

 

Drivers head is cracked between the valves, I didn't bother pulling the passenger side off after seeing this. Head gasket looked fine, but I didn't expect to see too much of an issue since I wasn't mixing coolant and oil.

Now, do I replace the heads and hope for the best, or spend the extra to get a short block along with the heads? With the engine being around 125PSI it seems kind of beat at this point. Could cracked heads cause that much of a compression loss? This is my work truck so I'd rather not have it down again anytime soon to replace the bottom end. If its best to replace the whole motor at this point I'd rather do that and get it done. I need this truck for plowing. Edit: I also have little way of knowing how hard the truck was used before. The owner used it a couple times a year to tow a small boat and to plow his driveway. Tow hitch and plow are dated from only a few years ago. I noticed when driving this truck on the freeway the exhaust manifolds would glow at the center two cylinders, both sides, I was expecting the Cat to glow from the oil from the plenum leak, but it was fine. Just the mani's glow. I have had clogged cats before in other vehicles and noticed they would start glowing before the exhaust manifold. For all I know the previous owner had this happening each time he drove it and either didn't notice or did nothing about it.

 

Which side head was cracked? You state passenger side, but, then next, you say you didn't pull the passenger side.....

If this is your work truck, that you depend on to make you money, buy a long block, and replace the motor. That way, you KNOW that everything is good, and you won't have to worry about it for another 100K+ miles.

 

Fixed it. Driver's side was cracked.

So far everyone I have talked to says to just buy a long block, so thats kind of reassuring. Guess its time to start shopping around. I said short block and heads before because I have found a few bottom ends in my $$ range, but they come with stock heads. I'd rather buy Iron Rams or some other upgraded head to rid the chance of them cracking. I'd also like to put in my aluminum plenum while I'm at replacing the motor.

If I knew I was going to be spending this much I would have bought a diesel. I shouldn't have let myself get talked into buying this truck before I could do a compression test and run it first thing in the morning... I have a feeling the previous owner knew what was going on. While taking the head off I could tell quite a bit had been 'touched' recently between loose bolts, marks on bolts and some broken clips-holding the plug wires and the injector clips on the driver's side. The driver's side valve cover gasket leak looked fresh for a reason, whoever was messing with it left some of the nuts loose and a couple were slightly stripped.

Well, anways, I've got about $4500 to play with. I'd like to keep it as cheap as possible to do it right with upgraded heads that won't crack. Any suggestions? Def willing to do a 5.9 over the 5.2. Seems pointless to replace a 5.2 with another 5.2. I've also heard good things about using an 'RV' cam for the low end grunt (can't remember the specs off the top of my head right now).

 

Another member just went thru this, for slightly different reasons..... Check his thread here.

 

If there's no excessive exhaust restriction, then that's a sign of a very lean air/fuel mixture. Either cause is very, very bad for the engine and will cause failure soon enough if it's not corrected.