Stock Vehicle Maintenance

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

seanb98

OBS Enthusiast
Joined
Mar 4, 2017
Messages
55
Reaction score
54
Location
Grants Pass, OR
The block has two drain plugs located about mid engine, just above the oil pan flange. On the passenger side the plug is also the knock sensor. On the driver side it's a hex head bolt about 9/16ths. Both are male pipe fitting tapered threads.
If you do the lower intake gaskets, you might consider draining the coolant. You can re use it if you can catch it.
The gaskets are famous for failing but the reason why is up for debate. Common theory holds that Dexcool eats the gaskets. Others call BS. Either way it's a common problem.
You can do it in a weekend if you are handy with a wrench. You need the Felpro gasket kit and a tube of RTV. You unplug most of the harness and lay it over on the driver's side. Then you unbolt the ac compressor and lay it over on the passenger side. Other than that, the hardest part is pulling the distributor. You have to put it back exactly how you found it. There are lots of great videos on Youtube.
Thanks for the info! If the distributor needs pulled, won't it need timed with a scan tool as someotherguy mentioned above in the case of the distributor gear replacement?

What are you using the RTV for? Most gasket kits are typically assembled dry for best sealing.

I'm sure it's far less than a weekend job, probably only a few hours for me. I am fully outfitted with tools (not a scan tool unfortunately) and have significant background turning wrenches. This suburban I have actually turned into a service rig loaded down with all my tools in order to free up the bed space in my pickup for other uses.

Anyway, it all sounds easy enough, but I'm the type of guy that likes to go into a job prepared rather than dive in and spend time later scratching my head over some little mystery item I am not familiar with. Hence all the questions ahead of time.
 

tinfoil_hat

I'm Awesome
Joined
Nov 18, 2016
Messages
309
Reaction score
169
Location
Sparks, NV
You need the RTV for the engine valley. The gaskets seal to the heads around the intake ports and coolant passages. You run a bead across the block and up either side of the head about 1.5", put the gaskets down, then lap the same 1.5" over the gasket again. I think they even give you a small tube in the Felpro kit. They also give you the gasket for the upper intake and an o-ring for the fuel line. Speaking of which, this is also the best time to upgrade the fuel spider. SPFI to MPFI, or whatever. Unfortunately this is a $350 part. You can also replace just the fuel poppets but they are like $40 each. Might as well just do the whole unit.

The distributor should not need to be timed if you can put it back exactly how you found it. The idea is to make several reference marks on the dizzy and the manifold, or the firewall. Mine ran exactly the same before and after and I'm a klutz.

Weekend job is probably about right. It isn't a hard job but there is some fiddling.
I think I have read quotes of about $600 in labor from a shop, if that gives you some idea.
 
Last edited:

seanb98

OBS Enthusiast
Joined
Mar 4, 2017
Messages
55
Reaction score
54
Location
Grants Pass, OR
You need the RTV for the engine valley. The gaskets seal to the heads around the intake ports and coolant passages. You run a bead across the block and up either side of the head about 1.5", put the gaskets down, then lap the same 1.5" over the gasket again. I think they even give you a small tube in the Felpro kit. They also give you the gasket for the upper intake and an o-ring for the fuel line. Speaking of which, this is also the best time to upgrade the fuel spider. SPFI to MPFI, or whatever. Unfortunately this is a $350 part. You can also replace just the fuel poppets but they are like $40 each. Might as well just do the whole unit.

The distributor should not need to be timed if you can put it back exactly how you found it. The idea is to make several reference marks on the dizzy and the manifold, or the firewall. Mine ran exactly the same before and after and I'm a klutz.

Weekend job is probably about right. It isn't a hard job but there is some fiddling.
I think I have read quotes of about $600 in labor from a shop, if that gives you some idea.
Makes sense. Thanks for the explanation! But what is this fuel spider thing? You did lose me there...
 

tinfoil_hat

I'm Awesome
Joined
Nov 18, 2016
Messages
309
Reaction score
169
Location
Sparks, NV
Makes sense. Thanks for the explanation! But what is this fuel spider thing? You did lose me there...

This is the fuel injection system. A central fuel metering gadget that perches on top of the LIM like a bug or some kind of sea creature. It has eight hoses for legs, each tipped with a poppet that sprays fuel into the intake ports. The old style is a mechanical poppet 96-2001. After that they went to a poppet with an electronic injector at the tip. The older poppets become clogged with carbon over time or they fail to seal after the fuel pulse. This leads to rough running, hard starts, missing, poor idle, lost fuel economy, etc.
The upgrade to the new style is plug and play, as I understand it.
 

seanb98

OBS Enthusiast
Joined
Mar 4, 2017
Messages
55
Reaction score
54
Location
Grants Pass, OR
This is the fuel injection system. A central fuel metering gadget that perches on top of the LIM like a bug or some kind of sea creature. It has eight hoses for legs, each tipped with a poppet that sprays fuel into the intake ports. The old style is a mechanical poppet 96-2001. After that they went to a poppet with an electronic injector at the tip. The older poppets become clogged with carbon over time or they fail to seal after the fuel pulse. This leads to rough running, hard starts, missing, poor idle, lost fuel economy, etc.
The upgrade to the new style is plug and play, as I understand it.
Oh, I get what you are talking about now. But mine is stilling running like a top, so I'll leave that part well enough alone for now. I understand how the fuel injection system works, but your terminology threw me off.

But that also brings me back to the intake manifold gasket, since mine runs so well is there any reason to get into that at this point? Should create a vacuum leak when there is an issue, and thus causes a rough idle, correct? Symptoms I am not currently experiencing.
 

tinfoil_hat

I'm Awesome
Joined
Nov 18, 2016
Messages
309
Reaction score
169
Location
Sparks, NV
Fuel spider is the common name for the fuel injection unit. When you see one you will get why. Vacuum leak would usually be at the upper manifold. When the lower goes it allows coolant into the combustion chamber. You may also see seepage coming through the gaskets. Alternatively, you might not see a leak but you may notice loss of coolant as it is consumed or sludging of the Dex from contact with air. You might also hear gurgling in the reservoir after shutting the vehicle off.
If your truck is running fine and you aren't losing coolant then by all means, put it off. Just understand that it is more a matter of when, not if. LIM gasket failure is the single biggest complaint with these engines.
 

someotherguy

I'm Awesome
Joined
Sep 28, 2013
Messages
9,803
Reaction score
14,168
Location
Houston TX
Thank you for all the helpful info! I'll definitely be replacing the ignition lock cylinder, it sounds pretty easy.

It does look like I have the G80 option. So, is it really going to hurt anything having the limited slip additive in there, or is just recommended not to use it because it decreases the lockers ability to function as designed? I don't really care if the locker properly functions or not as long as it isn't going to cause any damage having the additive in there.

Would be kind of interesting to know what all those other codes are.

You must be registered for see images attach
The additive can cause problems with the Gov-loc, doesn't mean it will, but it can. If you hear any chattering noises from back there or it seems like it's engaging/disengaging when you don't expect it to then you should consider changing the lube out.

You can decode most of the RPO's a few different ways.

1. If you've got a friendly dealer nearby you can get a vehicle build report by giving them your VIN. For later trucks like yours, the report is usually detailed with what each RPO means. Older trucks it'll just be the same list of codes the sticker shows, unfortunately.

2. You could run the VIN through a site like compnine, but you'll pay a few bucks for the privilege.

3. You can decode them yourself by searching for each code through an online RPO listing (which is monstrous but easily searched) though just beware that some RPO's get recycled, so you may see a result that doesn't make sense. G80 is one of them, and in other applications (car vs. pickup) it does mean limited slip instead of locker. Some of those codes are just "sales option" codes and won't decode at all. Here's a pretty complete and useful list: www.someotherplace.com/info/RPO.pdf

Richard
 

someotherguy

I'm Awesome
Joined
Sep 28, 2013
Messages
9,803
Reaction score
14,168
Location
Houston TX
For example, here's a printout from the dealer - the age break at which you just get the list vs. list with descriptions seems to be 1995-1996. All my 1995 and older stuff I just got the list, 1996-up came with descriptions...though I did have one 1998 come back with just the list, so who knows...

http://www.someotherplace.com/bb/inv/3474_rpo.pdf

Richard
 

df2x4

4L60E Destroyer
Staff member
Super Moderator
Joined
Mar 1, 2012
Messages
11,159
Reaction score
12,702
Location
Missouri
^ Great info here.

I'll second the mention of www.compnine.com. $5 gets you a detailed lookup on five VINs. One of the best $5 purchases I've ever made. It will give you a comprehensive list of all the options on the truck, with no worries about recycled RPO confusion like Richard mentioned. Dealer lookup would probably be cheaper (free), but the CompNine lookup can be done without ever leaving the house.
 

skylark

I'm Awesome
Joined
Nov 15, 2011
Messages
7,839
Reaction score
7,659
Location
Grants Pass, OR
If you need to reset the distributor, I have a scanner that will do it. I just so happen to live in Grants Pass as well.
 
Top