5.3 Engine Change In 2000 Silverado

AirForceAngler · August 29, 2007

Has anyone changed out an 5.3 in a NBS? Mine has had a coolant leak for some time and I finally got around to changing the head gaskets. What I saw when I opened it up was scary. Lots of engine sludge under the passenger side valve cover and that butterscotch snot stuff from coolant in the oil under the other. Went ahead and changed the head gaskets and buttoned it all back up and when I went to change the oil, I pulled the plug and nothing came out. Sludge had built up down there so thick it covered the drain hole. Not sure what has caused this. The truck has 115K on it and I've been running Mobile 1 for about 30K, changing every 5000 miles. Ran Castrol GTX before that. I'm thinking it has something to do with coolant in the oil, it has been slowly using coolant for about 2 years - half a gallon every 3000 miles but got worse recently.

Well, not being sure how long this engine will last now, I picked up a salvage 5.3 with 50K on it and will be changing it out soon. The Chiltons manual says to disconnect the A/C compressor and remove it to include draining the freon. Since this is on the bottom of the motor, couldn't I just unbolt it and wire it out of the way? What else should I be ready for when pulling the old one out.

Thanks for the help!

Wingnut · August 29, 2007

ls1truck.com has a lot of guys doing this conversion.

AirForceAngler · August 30, 2007

Thanks, I'll check them out, but it isn't any kind of conversion, just a replacement.

99Silver6.0 · August 30, 2007

Really a simple, simple swap. Unbolt everything and go to town. And NO the compressor does not have to come out. Pull it out of the way with some bungee straps. Done deal. Watch the oil pressure sender at the back of the valley. That little bastard breaks really easily.

Another tricky area is the bell housing bolts. Now you CAN take it all out as one combo deal. Engine and trans. Yes it will fit! Been there done that when I put the 6.0 in my old 99. Yet another spot that can cause headaches is the locating dowels on the rear of the engine. Sometimes they do not want to let go of the tranny. Before bolting the new engine back to the tranny, be sure to clean those dowels with emery cloth. My friend broke the bell housing on his tranny because one dowel was so caked with crap. It wouldnt pull together. So he kept tightening a bolt till I heard a loud POP from above the truck. That was a mess.

AirForceAngler · August 30, 2007

Thanks, 99. All them wires are a real mess, had to deal with that when pulling the heads off for gaskets.

On a similar topic, did you put a 6.0 into a 1500? I was thinking of doing that but wasn't sure how much was involved and I can't afford to have the truck down for too long to figure it out. I got a decent deal on the 5.3 also so that's what's going back in. I don't have to turn in my old motor so I will have that on the stand to play with some also. May look at putting a cam in it with bigger rockers and some other stuff. It will probably have to be bored out a bit also if it can.

99Silver6.0 · August 30, 2007

Thanks, 99. All them wires are a real mess, had to deal with that when pulling the heads off for gaskets.

On a similar topic, did you put a 6.0 into a 1500? I was thinking of doing that but wasn't sure how much was involved and I can't afford to have the truck down for too long to figure it out. I got a decent deal on the 5.3 also so that's what's going back in. I don't have to turn in my old motor so I will have that on the stand to play with some also. May look at putting a cam in it with bigger rockers and some other stuff. It will probably have to be bored out a bit also if it can.

Yea I put one in my 99 1/2 ton. I payed $1250 for the motor complete from intake to oil pan. There is no thought invloved. It is the same motor externally!! Everything from your 5.3 will bolt to the 6.0. And I mean everything! JReally only big thing is you just gotta take the 6.0 flexplate loose, get rid of the crank spacer thats used for the 4L80 and bolt on the 5.3 flexplate. I didnt have to give mine up as a core either.

As for doing mods while the motors on the stand. Thats ideal!!! Cam is simple anyway. But the oil pump sucks big time when you do it in the truck. If your gonna mod it, do it NOW! As for the rockers, leave the stock 1.7's on there. Unless your gonna get a non-adjustable rocker dont even mess with them at all. Most of the time the ramp rates on say Comps XER is too much with the added rate the rockers induce. Quite a few cam grinders actually say not to use 1.8 or 1.85 rockers with their cams. Stock rockers are already roller fulcrum too.

Wingnut · August 30, 2007

I'd love to swap a 5.3 (or even a 6.0) into Fred in place of the 4.3....Wonder how long the tranny would hold up.

AirForceAngler · August 30, 2007

I'd love to swap a 5.3 (or even a 6.0) into Fred in place of the 4.3....Wonder how long the tranny would hold up.

That was going to be my next question also if I had put a 6.0 in. I guess as long as you didn't get on it too much it might last. With 115K on mine, I'm expecting it to go at anytime anyway. Then I'd just have it redone with some stouter parts. I'm going to do that anyway when it goes because I do do some heavy towing.