noisy injectors?

[coxfmly]

On acceleration my suburban sounds like my old mustang which had a bad case of pre-ignition, like a can of marbles. Could old or worn injectors sound like that? Sub has 208K miles, I have no idea how old they are.

thanks..

[DmaxMaverick]

It probably needs injectors. However, there are several other things that can cause noisy running. Fuel filter, air filter, timing, timing set, fuel pump, balancer, crank pulley, flex plate, torque converter, clutch/flywheel, accessory, can of marbles, or a real problem. If they are original, the injectors are past due. Same goes for the timing set, and possibly the pump.

[coxfmly]

yikes, ignorance is bliss at times. quite a bit to think about but its a starting point. The fuel filter, lift pump & air filter are new. The previous owner (original) had mentioned that the pump was replaced by G.M. under a warranty program around 100k or so. He never mentioned injectors or timing set. Ive had the timing set recently and have mentioned the noise to my mechanic. He didn't think much of it, but it drives me crazy. I must say that the "rattle can" inst usually during hard acceleration but during moderate throttle. my 6.2 never sounded this way. I know that with 208k, I'm probably it the last of days with this engine. I would like to get to 250k but that's not too far down the road with the miles I drive.

[coxfmly]

yikes, ignorance is bliss! quite a bit to think about but its a starting point. The fuel filter, lift pump & air filter are new. The previous owner (original) had mentioned that the pump was replaced by G.M. under a warranty program around 100k or so. He never mentioned injectors or timing set. Ive had the timing set recently by my mechanic and have mentioned the noise, he didn't think much of it. I must say that the "rattle can" inst usually during hard acceleration but during moderate throttle. my 6.2 never sounded this way.

I know that with 208k, I'm probably it the last of days with this engine. I would like to get to 250k which isn't too far down the road with the miles I drive. Ive started to look into replacement engines, but who do you trust. I contacted AM General seeking information, but their E-mail address they wanted me to use for correspondence wouldn't work for some reason ?

I still have my 84, 6.2 that has 140k that could be freshened up but I'm not sure if that would be a good choice. Engine went south when the head gasket blew :( It sure would be nice to have a kit to re-engine a suburban with a Cummins or Duramax. Unfortunately, it seems that once these engine go, so does the vehicle. It would be great if G.M. had a "crate" 6.5.

Thanks for the direction forward.....

[Robyn]

The 94 has a DS4 injection system (electronic) and these engines make a lot more rattle than the old 6.2 's did.

If the TDC offset/timing are set a tad off, these can get pretty rattly.

Now the Coolant temp sensor can fail to shut down the cold advance, but the ECM should set a code if the advance stays on too long.

Check for any DTC's (Trouble codes)

The injectors can be in sad shape and cause noisy combustion too.\


Keep us posted

Missy

[DmaxMaverick]

Well, you have 2 Suburbans listed in your sig, and failed to mention which one.

The 6.5TD is noisier than a 6.2, both being equally healthy. Even brand new, they can sound like a can o' marbles at moderate throttle, especially when cold.

If electronic, a failed temp sensor (prevent the cold advance from shutting off) will set a DTC, and trip the SES lamp. If the engine, while running, or ignition on, doesn't warm up according to a specific table, it will code.

If mechanical, the HPCA (Housing Pressure Cold Advance) can hang up for a few reasons. You can test this by applying 12V to the HPCA wire (rearmost wire on the pump) once it is warmed up greater than 140°. If the HPCA is working properly, you will hear the timing advance, and the can o' marbles.

If electronic (94), the timing won't move around on you. Once set, it stays set until you "change" something.

By "timing set", I meant the chain/sprockets, not necessarily setting the timing. If mechanical (84), the pump timing needs to be periodically advanced a tad to keep it optimal, due to timing set wear. The electronic timing is adjusted according to the crank sensor, so the pump stays in time with the crank. The valves, however, start to fall behind as the set wears. The mechanical pumps stay timed with the cam/valves, but fall behind the crank, as the set wears. Since you have both (assuming you still have the two in your sig.), all this information may be helpful.

At 208K, it needs some predictable maintenance items, such as in the list above. Perhaps add head gaskets, as the need arises. If you plan on keeping it for a while (few years, lots of miles), replace the gaskets when it's convenient. They won't "fail" (leak) when it's convenient. The other items should be replaced as you can work them in. Normally, if it makes it to 200K without any significant long block issues, 250K is no problem. It's the stuff bolted to the engine than will usually be the source of problems at this point.

[coxfmly]

Unfortunately the 84 has been put out to pasture. The 94 has new heads from clearwater (198k). I have checked the codes and everything is fine. It does run O.K., bit of blow by, but i'm still averaging 17 mpg..Unfortunately I didn't think about getting the actual psi when I had the injectors checked. They said they were squirting o.k. and I think they mentioned 1800 psi or so? If im not mistaken I should be over 2000 psi right?

[Robyn]

1800 is a tad low, 2000 to 2100 is about where they should be.

I like 2000 on a used IP.

As long as the spray is even and not a pee stream you can get by.

The higher the pop pressure the more rattle you get.

Sounds like the timing may be a tad advanced.

If the TDCO is up at near -1.94 these suckers will cackle pretty good.

On a cold morning they will make a powerstroke cringe.


Missy
The more you get past -1.5 TDCO the rattle gets louder really quick.

[coxfmly]

"The more you get past -1.5 TDCO the rattle gets louder really quick........"

Is it difficult to adjust the TDCO?