Hello everyone,
I’ve owned a ‘01 24-valve for about a year now, but I just purchased a decent looking ’96 12-valve with 90k miles on it. Since I’m brand new to the 12-valve world, I hope you guys can help with a few dumb questions. First, I noticed that there are very light puffs of white blow-by smoke coming out of the downdraft tube, and the oil fill tube, is this normal for a 12-valve? Also how much oil should these motors burn, my 24-valve uses about one quart every 4-5k miles? My second question is about a ticking/clacking noise that I hear under the truck. I hear it about where the muffler is so I checked for exhaust leaks, but found none. If it was a gas engine I’d guess it was a bad lifter, but I don’t hear anything (except the normal rattle) near the engine, could it be that the valves need adjusting? Third and last, it takes the engine about 2 or 3 seconds of cranking before it fires up, whereas my 24-valve starts in about a half of second with just a tap of the starter. I found another posting that said to check the idle speed and for bad fuel hoses, any other suggestions or is this long cranking time normal for a 12-valve? Thank you.

 

It's the fuel Lines more than Likly mine was doing the same thing until I found the leaking line and replaced it,as far as the blow by goes I'm not sure and my engine with 130000 dosn't use any oil.....

 

Welcome aboard ! The 12V's definitetly sound different but it sounds like it might be time to get your valves adjusted, and while your doing that go ahead and bump your timing to 16 degrees. It really runs a lot better. As far as the long cranking time, my '96 cranks almost as soon as I touch the key. I did have a fuel hose deteriorate once and caused fuel drainback, but this caused like 20 seconds or more of cranking....man it took forever it seemed like. It still could be a airleak in the fuel system somewhere. My guess is its related to that.

 

The clicking on a lot of trucks seems to be the overflow valve with a weak spring. Some lift pumps on the truck's will tick when theystart to go.

And for oil consumption, I'm at 340K and I use about a half a quart in 10K miles. And the blowby? I've never felt the 12V's have adequate ventilation. My biggest problem is tranny gaskets leaking.

..Preston..

 

I have a 97 and found it to be using oil as well... as a protective undercoating for the oil pan, front diff and tranny from the front main and rear main leaking. May check to make sure you're not leaking it instead of burning it.

As for the cranking, mine makes 2 revolutions and fires, I've heard more and less than that. Check the fuel lines like others have suggested and check the lift pump as well (which "could" explain the tick as well). I have a tick as well, but am pretty confident after some probing that either the wrist pin or a piston skirt on ol' number 1 has seen better days.

Also, make sure your idle is set high enough...

 

Hmm lets start easy here

At 90K im sure that for sure your idle needs to be bumped up, is the truck completely stock? whats it running in gear? and out of gear with AC on? it might need to bump up the idle to ease in hard starting. The ticking and clacketing noise could be the OFV, or the LP goin out as Abbynormal said. I have a 1996 and at half a turn or a turn at most, without any pedal it fires right up. My idle is at 750 or so with AC on, and 850 without it on. It starts easy. I assume that the truck is stock, NO gsk no nothing, (that will change soon im sure ) So it cannot be that ur springs are outta whack.

The return lines on these trucks are rubber and tend to pick up air which will result in hard starting and or even a power loss.

I have never had blowby of the turbo on my truck, but i have tightened my oil retun line on it before, so i cannot help u with that..

Hope this still helps tho

Rick

 

If the ticking seems to be coming from the passenger side check if the exhaust manifold is cracked or the bolts are loose. You will need a mirror. Sure fire way to tell if a hard look is necessary is if the #1 or 6 manifold bolts are bent.

 

Thanks guys, all of you have been a great help. I’ll replace the rubber fuel lines for starters with good diesel rated ones, and I’ll double check the idle speed. The engine starts in 2 to 4 revolutions, with no ‘gas pedal’ pressure. The ticking noise definitely seems to be coming from the passenger’s side, but you can hear it everywhere, if you hold your ear close by, it actually seems to be coming from inside the exhaust tubing. The other place I can hear it very clearly is on top of the engine, near the valve covers. The ticking always there, but it does get louder and quieter at random. I hope its something like an exhaust leak, or a fuel system problem, and not something internal like a wrist pin or piston skirt-that would really suck. Thanks again everybody.

 

"The other place I can hear it very clearly is on top of the engine, near the valve covers."

If the noise is loudest at the top then the valves need to be adjusted.