rear differential

sonoma driver · April 11, 2005

I have recently bought a 1993 gmc sonoma 2.8 l engine and I ahve tried to check the differential fluid but it seems the refill cap is rusted or fused on.

Is there any way I can take this off without stripping the square hole?

Or do I have to take it to a mechanic with the right tools?

PeterbiltChrome · April 11, 2005

penetrating oil with a little heat carefully applied...... find a torch and heat around the plug, not the square hole!

no-sieze that plug next from here on out

snoman · April 12, 2005

I have recently bought a 1993 gmc sonoma 2.8 l engine and I ahve tried to check the differential fluid but it seems the refill cap is rusted or fused on.
Is there any way I can take this off without stripping the square hole?

Or do I have to take it to a mechanic with the right tools?

<{POST_SNAPBACK}>

Try a air driven impact wrench of the proper drive size as a lot of times the vibration from it will free rusted bolts that cannot be freed otherwise.

sonoma driver · April 12, 2005

thanks alot I will try heating it up tomarrow

I would try the air impact wrench but I dont have an air compressor to do it(If it is what I think you are talking about).

if you think of anything else post it up and I will see if i can give it a try

snoman · April 12, 2005

thanks alot I will try heating it up tomarrow

I would try the air impact wrench but I dont have an air compressor to do it(If it is what I think you are talking about).

if you think of anything else post it up and I will see if i can give it a try

<{POST_SNAPBACK}>

Heat will be kinda futile is cover is still on diff as the housing will shunt some of the heat away unless you have a very hot torch. I would take cover off and clamp it in a vise with a rag to slow heat transfer and heat the plug and the case around it to dull red then insert a driver into it which will start cooling and shrinking nut first and try to break it loose.

blue2kzr2 · April 12, 2005

thanks alot I will try heating it up tomarrow

I would try the air impact wrench but I dont have an air compressor to do it(If it is what I think you are talking about).

if you think of anything else post it up and I will see if i can give it a try

<{POST_SNAPBACK}>

Heat will be kinda futile is cover is still on diff as the housing will shunt some of the heat away unless you have a very hot torch. I would take cover off and clamp it in a vise with a rag to slow heat transfer and heat the plug and the case around it to dull red then insert a driver into it which will start cooling and shrinking nut first and try to break it loose.

<{POST_SNAPBACK}>

Not really sure how clamping the cover in a vise will help. The fill plug is in the housing. That's how my 94 was, that's how my 2000 is.

I wouldn't suggest taking the cover off unless you're SURE you can get lube back in there.

snoman · April 12, 2005

thanks alot I will try heating it up tomarrow

I would try the air impact wrench but I dont have an air compressor to do it(If it is what I think you are talking about).

if you think of anything else post it up and I will see if i can give it a try

<{POST_SNAPBACK}>

Heat will be kinda futile is cover is still on diff as the housing will shunt some of the heat away unless you have a very hot torch. I would take cover off and clamp it in a vise with a rag to slow heat transfer and heat the plug and the case around it to dull red then insert a driver into it which will start cooling and shrinking nut first and try to break it loose.

<{POST_SNAPBACK}>

Not really sure how clamping the cover in a vise will help. The fill plug is in the housing. That's how my 94 was, that's how my 2000 is.

I wouldn't suggest taking the cover off unless you're SURE you can get lube back in there.

<{POST_SNAPBACK}>

Opps, I was thinking a differrent cover. Since it is in housing, it will take a LOT of heat to break it free but I still think I would take cover of to clean inside of housing from possible burnt oil residue after you heat it. Sometimes those plugs are just pretty tight and not really rusted.

Also, you can try putting a "wrench" on it and pulling as hard as possible and while doing so smack the housing next to the plug with a hammer as sometimes the vibration for this can break it lose as well.

sonoma driver · April 19, 2005

I have not been able to get to it yet besides with adding liquid wrench every day to it. but it seems like the bolt has started to strip because when i turn it, it seems to be the wrong size when i know its the right size. can I use a cut up pop can and wrap the extension in that to fill the gap or are there easy out reverse screws I can buy?

snoman · April 19, 2005

I have not been able to get to it yet besides with adding liquid wrench every day to it. but it seems like the bolt has started to strip because when i turn it, it seems to be the wrong size when i know its the right size. can I use a cut up pop can and wrap the extension in that to fill the gap or are there easy out reverse screws I can buy?

<{POST_SNAPBACK}>

Some ot those plugs are hot fit (put into casing while it is still warm are casting and machining) and together with the plugs has a pipe thread on it too (which gets bigger in diameter) the further it is in for a crush fit (it will not break lose like a bolt). At this stage you might be best to install a fill plug in cover at the correct heigth because you seem to lacs the tools to get old one out. If you can manage to turn plug about 1/2 to 3/4's of a turn, it should get easier. Also liquid wrench is not going to help with this problem as rust is not problem a crush fit is. You could try getting a chuck of dry ice (which has a temp of 109 below zero in solid state) and press it HARD against plug for about 15 to 20 seconds and then use a wrench on it quickly after removing the dry ice and if it does not work, repeat proccess. The trick is to get the cold to shrink the plug before it gets fully into the case around plug and shrinks it too.

sonoma driver · May 1, 2005

ok I havent tried dry ice yet but I heated the outer case up but it didnt do much and currently I have it at high tension and seeing if for a weekend to loosen it up other wise i tried everything previously on here.

my uncle says that i shouldnt worry about it till 100k-150k miles

while my dad says the only way is to drill it out

Mighty HD · May 2, 2005

If it was me i would leave ti alone, or take it somewhere and have it done...lol

And stand there while they do it to ensure they do it..

snoman · May 2, 2005

ok I havent tried dry ice yet but I heated the outer case up but it didnt do much and currently I have it at high tension and seeing if for a weekend to loosen it up other wise i tried everything previously on here.

my uncle says that i shouldnt worry about it till 100k-150k miles

while my dad says the only way is to drill it out

<{POST_SNAPBACK}>

I would not drill it out because you can not be sure if filings are out of case that can damage internals (though you could use a few large magnets to try to catch filings) If you try to heat case again, heat it up then quicklu cool the plug with dry ice because just slowy heating the case will not work because the plug will heat and expand with case. You must establish a big sudden tempature differentail to causr the plug to shrink in the bore to break it lose.