Diesel engine noise

[Jon Klein]

When my SHO is cold, it sounds like a diesel engine at any rpm EXCEPT IDLE, then it goes away after the car is heated up. It also will randomly give me starting trouble, but only if the car is hot. Full 60K done 12,000mi ago. Cam sensor, crank sensor, Idle Air Bypass Valve, valve job, water pump, fuel pump, fuel system cleaning, tranny fluid change, brakes, all seals on engine, coolant flush, new oil cooler. This noise is really annoying...thought it could be cold oil but I only use Mobile 1 10w-30.

thanks

 

[shojuan]

Sounds like bad rod bearings.

Rick

 

[Jon Klein]

How much would it be for new rod bearings? How easy and about how long does it take to install. Should I just take it to the SHO shop?

 

[biker889]

rod bearings are under $100 from napa. so i hear. all you need to do is drop the oil pan, and the bearings are there. it would take a few hours, could do it in a day. just need to make sure you torque the bolts to the specific rating. im about to do this to my car, and i dont have any doubts.

 

[Off Road SHO]

well, It's a little more difficult than that, but not much. Some things that are in the way that will need to be removed and put back and torqued:

Y-pipe
starter
oil pan
main bearing brace
oil pump pick-up and brace

Now you're at your rod bearings. Do one at at time, label a ziplock baggie for each old bearing for future reference.
It's easier if you take out all your spark plugs (if your wells are clean) so you can rotate your engine with a ratchet on the front pulley nut.

Bring the number one rod down to the bottom of its' stroke so you can remove the rod cap nuts easily.
After that is done remove the rod cap and its' respective bearing half. Put the bearing in the baggie.

Using a wooden hammer handle, lightly tap on the rod bolt end to move the rod away from the crank a little. I usually just lay the end of the handle against the rod bolt and hit the head end of the hammer with the palm of my hand. If you took the spark plugs out before hand, you might be able to just push the two rod bolts (and the rod) up towards the top of the engine. You can also put two short pieces of rubber hose on the rod bolts to protect the crank. You only have to move it far enough to remove the upper half of the rod bearing. Put it in the baggie also.

Grab a new bearing and do not oil it up right now because you're going to make sure that you have the right size bearings FIRST. Clean all oil off of rod, cap and crank journal. Put a new bearing half into the rod half and the cap half. Notice the dimples in the bearings and the indents in the rod and cap where the dimples have to go.

Cut a piece of Plasti-Gage, that you got from the same place where you got your bearings and lay it across the width of the rod cap, on top of the new bearing but make sure it doesn't line up with an oil hole.

Bring the rod with new bearing back down to the crank and fit the cap with its' new bearing back on. I like to keep my thumbs between the rod bolts and the crank journal to ensure that the journal is not scratched. The rod cap has an arrow like design on the bottom of it that must point towards the front (waterpump end) of the motor.

Snug up the cap nuts and then torque in two stages. After torqueing, un-do the nuts again and remove only the rod cap half. The plasti-gage that you put in will be smashed to a certain width. The package that the Plasti-gage came in has width markings on it. You just match up your width with one on the package to see how close the bearing got to the crank.

If the gap is about .002 to .004", you're in good shape. Scrape that Plasti-gage residue off of the cap bearing and crank journal with a finger nail. Push the rod back up again and put some STP oil treatment or engine assembly **** on the crank journal. Do not skimp in this process. It is messy but very important. This **** is the only lubricant your new bearings will see for their first 183 revolutions!!

Don't ask me how I know this, but DO NOT assume that the people who made the bearings, packaged the bearings or did anything along the way with the bearings, are perfect in their jobs.

I would plasti-gage each rod bearing to be absolutely sure. After all six have been done in turn ( so that you don't get cap #2 on rod #6), re-assemble everything. USE A TORQUE WRENCH! Put a new gasket on the oil pick-up tube to block interface or use a good silicone but sparingly.

Fill it with good oil. If you can figure out a way to crank over your engine with the starter but not have it start (or fire the fuel injectors for that matter) you will be able to prime the oil passages before it fires up for real. That would help pre-**** the bearings.

Sorry to be so long winded but I think a lot of guys on the Forum want to do this but don't know how.

Tom

 

[Jon Klein]

Thank you so much... that will be extreamly helpful. I am in the process of ordering the bearings and I will use your doctrine to install them this weekend.

Many thanks,

Jon

 

[rangerj]

Jon,

A dieseling sound could just as easily be in the valve train. If you just had a 60K service your timing belt could be off a tooth and the clatter you are getting coud be detonation or pinging.

Are you using low octain fuel? If you anti-knock sensor is not functioning, and therefor not retarding the timing when it senses a detonation, this could also be the cause.

Check your "codes" for faults, or electronic failures. Find a mechanic with a top notch reputation to listen to noise your engine is making. We can only guess.

Tom's disertation on changeing rod bearings is A-one. The only thing I would add is that I strongly believe in using new bolts. Rod bolts, head bolts, and crankshaft main bearing bolts, are good for being torqued three times.

If you are not going to replace the bolts as a matter of course, then you should at least check the bolts for "stretch". Lay a straight edge on the threads. If all threads are not touching the straight edge, the bolt is stretched, and must be replaced.

As I said, my personal preferance is to replace the bolts. This is ESPECIALLY true for an engine that is intended to rev in the 6000 to 7000 RPM range (like the SHO)! Why risk trashing an engine for a few bucks worth of bolts? Hope this helps, rangerj

 

[Bizzy]

Tom...this is great material. Thanks for posting it up for everybody! Would you happen to have pics along the way to go with it by chance? Some times visuals are a big help too. thumbs_u

 

[BeatDaSHO]

hmm....what u could be hearing is an intermittent fuel injector. This would cause the engine to start on 5 cylinder thus hearing a miss in the engine (kind of like a diesel sound). Then the fuel injector might come alive. if this is the case, i'm sure that the fuel injector that is bad will finally just go out completely. I know what ur talking about with the diesel sound because my brother's SHO did the same thing and it would idle for like a minute on 5 cylinders. Then everything would be normal again. check it out.

Greg

 

[gosho89]

Jon I work on a sho yesterday (93 ATX 154K) with that very same complaint, I was there to do his valve adjustment, but once I opened the valve covers I found one of the cam-chain tensioners was missing the plastic/nylon strip the chain rides on. I left the motor open and am waiting for the new tensioners to arrive. $80.00 for the RH head and $50.00 for the LH head.

Heres some more information on this failure with pitures http://www.shoforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=17;t=004595

<small>[ December 07, 2002, 03:42 PM: Message edited by: gosho89 ]</small>

 

[DavidT]

gosho,
How often/when does it make the noise... all the time?

 

[gosho89]

The owner said it started out just doing it once in awhile, the owner continued to drive the car and the noise got progressively worse, now it does it all the time. When he started it for me it reminded me of my neighbors Cummins diesel powered Dodge p/u.

<small>[ December 07, 2002, 05:14 PM: Message edited by: gosho89 ]</small>