Loud Screeching Noise on a Chevy Blazer

wesx

I have a 98' Blazer and just had the transmission replaced recently. Not really sure if that has anything to do with it but the other day I went to take the truck for a drive when it started screeching loudly while I was driving down the road. All the electrical started dimming and it seemed like it was starting to stall. I was able to get it back home and figure out when it would start screeching. It seems to do it when I pull the shifter down between D and 3. I barely pull it out of D and down into 3 and it squeels like crazy. I've had conflicting ideas of what it could be.

Any ideas?

tidester

The first thing I would check would be the belts.

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wesx

Thanks for the reply. I checked the belts and they seem to be fine. Someone told me that it could be the altenator going bad. Could the altenator be the cause?

tidester

Actually, I had the alternator belt in mind when I suggested looking at the belts. If it's not the belt then certainly it could be the alternator itself.

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jlflemmons

A bad bearing in the alternator can squeal like a slipping belt. Also, see if the problem is tied to turning the AC on or off. Could be a compressor trying to lock up.

wesx

Ok, took the serpentine belt off today and it's still producing the loud screeching noise when I pull the shifter through the gears.

Another interesting note is that I took the truck for a drive and held the shifter upwards and it did not make any noise at all. Could it be something in the steering column or could it be the transmission causing the problem?

It is leaking some kind of fluid from directly underneath the engine and it's also leaking fluid from the pumpkin ball in the rear. Might this also have something to do with it?

wesx

No ideas?

tidester

Have you followed through on jflemmons' suggestions?

The leaking fluids would have me concerned. Can you describe the fluid? Odor, viscosity, color? That might help someone diagnose your problem.

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wesx

Yep I have tried what jflemmons' suggested. When it's sitting in park you can turn on the AC and everything else and it's fine. It doesn't do anything until it's pulled out of park.

The fluids are a darker color. Like a dark brown. I checked both fluids that are leaking and they smell like the same fluid. Maybe these pictures could be of some assistance:

tidester

I wonder whether that could be differential/transmission oil or something from your power steering. Anyone with hands on experience - please jump in!

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jlflemmons

Okay, for the oil pan, check to see that all the oil pan bolts are tight. I have seen these back out and allow the oil pan gasket to leak. The good news is that the worst one I have seen did not leak once it was tightened back up. Surprised me, that usually doesn't work that way.

The differential is interesting. That is not the typical leak pattern for a bad gasket. I see a lot of rust on the cover, check carefully that there isn't a hole.

Re the squeal when put in gear; has this been in water? You might need to drop the tranny pan and check for water, dirty filter, etc.

duntov

Many times the oil pan drain plug treads will be stripped by a over zealous jiffy lube technician in an attempt to cover himself in case of a oil leak followed by an engine failure. The oil pan drain plug should not be torqued more than 18 lb, or you will risk stripping the threads in the caged nut in the oil pan. The drain plug should always be equipped with a fiber gasket which does most of the sealing. Often a technician or car owner will replace a pefectly good 1/2"-20 drain plug in an attempt to prevent a leak. Usually that will not seal the leak because the treads are stripped in the caged nut in the oil pan and not the threads in the drain plug. . If the caged nut in the oil pan is stripped, the drain plug must be carefully replaced with a 1/2'-20 OS (over size) drain plug and new fiber gasket. The OS plug will not cut new threads in the caged nut but will chase (recondition) the present stripped threads in the nut. Always replace the fiber drain plug gasket after two or three oil changes. There are also double-oversize oil pan drain plugs, but do not use one of those until a single oversize drain plug does not seal. Some drain plug gaskets gaskets are nylon and may last longer. I have a 1988 Ford, 1999 Ford, and a 1991 S10 Blazer and every one has a stripped oil pan caged nut. That is because out of haste, I had the oil changed several times at the drive through quick lube "strip joints". ........Never again.

jlflemmons

Is the oil pan steel or cast aluminum? It appears to be the aluminum from the pictures, but hard to tell. The aluminum oil pan doesn't use a cage nut, it has threads in the casting, and uses a drain plug with a fitted neoprene gasket that is not replaced unless it leaks from a tear or such. Real pain in the butt to find the right one, too. Dealers have them, and a friendly mechanic might give you one. GM went to this design when they started using cast aluminum oil pans. I have seen them on V6 and V8 engines both.

duntov

I forgot about it being a cast aluminum oil pan. GM started installing cast aluinum oil pans on 1995 and newer S10 Blazers. My 1991 S10 Blazer 4WD has the deep steel pan with a caged nut. I had to install a 1/2"-20 OS drain plug in the pan thanks to a technician at a oil change strip joint.

The 1995-up S10 Blazer aluminum pan requires a M12 x 1.75 drain plug and that plug with an oversize thread can be purchased on-line at CG Enterprizes ( www.cgenterprises.com ) which is their #1027 drain plug and #2201 gasket. A better option would be to install CG Enterprises #1048 M12 x 1.75 OS double (piggy-back) drain plug and a #2201 gasket. You can install the OS double drain plug with Loctite #262 permanent thread locker and never have to remove the M12 x 1.75 drain plug again. In order to drain the oil, you remove the smaller "piggy-back" drain plug that is threaded into the main M12 x 1.75 drain plug that you have permanently locked in the pan with the Loctite thread locker.

The very last option would be to replace the oil pan with a new one. Unfortunately, you must remove the engine to do that. The high cost of replacing a oil pan is why the OS drain plugs and the piggy-back drain plugs were invented and introduced.

"When the price of eggs get high enough, roosters will start laying"

wesx

Ok, today I went out and rechecked all the fluids. All of the fluids were full and looked clean. The radiator was a little low on fluid but thats it. The fluid leaking on the ground under the differential is a light gold color.

I also played around with the shifter some more and it only makes the loud noise when it's put in to or taken out of drive. It doesn't do it with park, reverse, neutral, 3, 2 or 1.

I also noticed that the check engine light was on. I ran the codes and it came back with a bad O2 sensor. I also think that the catalytic converter is bad.

Could the cat be the cause of the loud noise?
Also, is replacing the cover for the differential difficult or is it just taking the bolts off and replacing the cover?

jlflemmons

Differential cover is easy. Pull the old one, clean all the gasket material from the carrier. Apply Permatex Black per the instructions on the tube, and reassemble. Will take about 1 2/3 quarts of synthetic 80W90.

Regarding the noise, any chance a heat shield is coming in contact with the linkage when in the drive position? May need to put this one on a lift to isolate the location.

The typical noise from a bad cat is a marbles in coffee can sound, or a loud sucking/whooshing sound if plugged.

A vacuum leak can trigger a false O2 sensor code. Several mechie's have told me the O2 sensor is the most common mistakenly identified failure around.