[Gutz66]

Need help.. Swapped a good 93' 350 Caprice Wagon motor into an 89' 4x4 Half ton Pickup. The engine has a deep hollow noise after the first start up. All of the sensors were used from the original engine. The chip is for a 305/350 ci. Engine runs good but still makes internal noise. Almost sounds like a rod. Oil pressure is good. Can't hear it while driving but once you stop and idle you can hear it again. Any thoughts? Many hours invested and near the end of our wits. Already tried posting in troubleshooting.

My concern at this point is if the dist. is off enough will the computer compensate and advance/retard the ignition and cause the knock?

Thanks

 

[Dean]

Double post

http://www.chevelles.com/forums/showthread.php?t=113172

 

[p-hanny]

On a `93 tbi the computer controls advance mostly unless it senses knock(thru the knock sensor located above the strater)) but even then I think it will only retatrd it so much. First thing I would do is check timing. Is it the 350 with the distributor located behind the water pump? If so pm me and I`ll give you some more info on that. There are crossfire problems those have. But I still say check timing first. Retard if you want to to tell you if its too advanced and the knock goes away. Look at the simplwe things first and then get worried after that, Paul

 

[Gutz66]

this is the rear mounted dist. the ignition check out ok and is good to go. the noise is a mechanical hollow knock/rub. does not sound like a rod. the belt was removed and noise still there. sounds like it is coming from the oil pan area. louder near the bottom of the engine. less towards the front and rear. more prominent in the middle. pulled the engine last week monday and was running strong with no problems. put in and noise started on the first startup. we used the same flywheel from the 350 and left the 305 flywheel on the bad motor. could that be causing this???? in the hurry that we were in we never checked it to make sure the same tooth count and o.d. diameter.
this is a car engine going into a 4x4 truck. auto trans. on both.

anymore thoughts?

 

[novaderrik]

did you keep the Caprice ecm ad use that in the truck? the truck engine has a flat tappet cam, and the Caprice has a roller. it might not make a difference, but by using the ecm for the flat tappet cam on a roller cam engine, your timing might be off and causing a lot of pinging or something.
also, check to make sure the flexplate isn't broken- my 92 Caprice had the flexplate seperate in a nice perfect circle around all the crankshaft bolts, but it still started and ran fine- except for the knocking noise when under load. got the flexplate out, and the middle of it fell right out when i tapped it with a hammer.

 

[quikss]

I had the same flexplate problem with my chevelle. Started it up one day and was running fine, all of a sudden it sounded like a rod broke, I was P.Oed. Crawled under and looked at the flexplate and it was cracked every which way.But it sure sounded like a rod was coming out the bottom end.

By the way, I could still start it fine, it just made a racket.

Jeff

 

[Derek69SS]

93' 350 Caprice Wagon motor

[thread hi-jack]what did you do with the body? I may be interested if you have the rest of the car [/thread hi-jack]

 

[bradford]

always looking for front end parts huh derek?

 

[bradford]

i would also check the flex plate. the noise will seem to go away under load with a cracked flex plate, because you are taking the load no load vibration out. also i would do some parts compatability. go to a parts store and compare parts such as knock, map, ignition module, if these parts have the same part number from the truck 305 to the caprice 350 then you should be fine. the ecm of the truck can somewhat compensate for a rich and lean condition in it's internal map. older systems had a set map on what the air fuel ratio should be at different rpm's, temp, map and altitude (baro). the newer systems are self learning and over a period of time can learn it's own and can create it's own map. ecm's have come along way!
also while you are at the parts store check the fuel injectors for the same part number along with the fuel preasure regulator. this should get you in the ballpark. also might want to check the local gm dealer and check ecm part numbers from the truck 305 verses the truck 350 of the same year. if it is the same part number but uses a different prom chip i would change it out. if i remember right back in the late 80's i was swaping the mass airflow sensor for the speed density system. the prom's ranged from $50-$75 at the time. hope this explains some for you.

 

[Gutz66]

thanks to all for your advice. turns out the oil pan did have a very small dent that we did not see and the windage tray was getting hit. must of damaged it during transportation. thanks again....

Derek,
sorry but the body has passed on to a better place.....rest in peace-caprice

 

[bradford]

glad you found the noise.