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  #1  
Old 03-27-2010, 11:52 PM
drb drb is offline
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Default Replacing Valve Stem Seals 96 4.3L

I'm replacing the valve stem seals on a 1996 Blazer 4WD with a VIN W 4.3 litre engine.

I've read through the posts here in the forum that I can find, but am confused about a couple of things:

1) I bought both the o-ring style seals and the umbrella seals. Not sure which ones I should use. In my web searching some people recommend using both. Some say the seals should go into the grove on the stem, other say they should not. Some say put the umbrella seal at the bottom of the stem and the o-ring in the grove at the top. I've been looking for a picture or diagram but so far have not found one.

2) Is there enough clearance to remove the drivers side valve cover with the air conditioning compressor bracket installed? I have the A/C compressor unbolted and out of the way, but the mounting bracket still hangs over the valve cover a little. Looks like it might be a bit of a trick to get the valve cover out.

3) Should the springs be removed before the new seals are installed? Some stuff I've read states that the springs should just be compressed, and the seals installed and then the keeper reinstalled and the compressor released.

Any guidance would be most helpful and appreciated.

Thanks in advance!

Darrell
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Old 03-28-2010, 12:57 AM
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Oh man, I read the title and thought you were talking about on your wheels. I was trying to figure out what kinda valve stems you were using that had seals! haha!
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Old 03-28-2010, 08:14 AM
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I believe you'll have to pull the compressor mount to get the valve cover off, but it wouldn't hurt to give it a go.

You will have to remove the springs to install the new seals. This can be accomplished with a spring compressor and forcing the valve closed using air pressure through the spark plug hole.

The umbrella type seals go down onto the head itself around the boss that the valve stem goes through. The o-ring type seals do the lower groove on the top of the valve stem. The upper groove on the valve stem is for the retainer locks.

If you decide to go with the o-ring style seals, the proper assembly order is to install the valve spring & retainer, compress the spring/retainer, install the o-ring into the lower groove and the locks into the upper groove, and finally release the spring/retainer. Use some oil to make it all go smoothly.

One thing I'll suggest is that you may want to go with both. It isn't a problem to be too dry on the valve stems.
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Old 03-31-2010, 10:32 PM
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Got the valve cover off the drivers side today and started to replace the valve seals.

The cover does come off without removing the A/C compressor bracket. I tried to take off the bracket, but looks like the power steering pump pulley would have to come off.

To get the cover off I had to remove the EGR hose from the intake manifold and then move the hose out of the way of the rear of the valve cover. Took a little fiddling, but the cover did come out.

Got the seals changed on cylinder #1. I was disappointed to find good condition umbrella seals already installed. Makes me wonder if the blue smoke from the exhaust is caused by something else. There are still 5 cylinders to do.

The number 1 cylinder spark plug was the only one that was not carboned up so perhaps I will still find some bad seals.

The compression test was good at 150 psi on all cylinders and the symptoms are classic valve stem symptoms, so we will see what tomorrow holds.

According to the Chilton manual, the 1996 engines should have the rocker arms that can just be torqued and do not require adjustments, but my rocker arms are not those type and will require adjustment.

Also the valves have only 1 grove. This is for the spring retainers.

So my valves have only 1 grove, umbrella seals, and the rocker arms are the type where the valve backlash has to be adjusted. Not what I expected in a 1996 VIN W engine. Perhaps the heads were replaced at some point in the past. Anyone want to take a guess as to the vintage of these heads?

The vehicle was made on 08/95 so perhaps they are 1995 heads, but then I would have expected two groves and oring style seals.

I will post tomorrow on what I find.

Darrell
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Old 04-01-2010, 06:11 AM
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They definitely are not '95 heads since the machining changed for the intake manifold bolting. Just must be throw overs in terms of the valves & rockers.
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Old 04-10-2010, 09:44 PM
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An update. The valve seals are fine. The problem is the valve guides. I can rock the valves considerably. This sucks.

Going to put the engine back together and sell the vehicle as I don't have the tools, time, or patience to fix it and having someone else fix it is going to cost way too much.

Picked up a nice Suburban, which is what we wanted anyways.

Darrell
Old 04-10-2010, 09:44 PM
 
 
 
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1996, 43, ac, blazer, body, bracket, chevy, cover, engine, guides, install, pictures, remove, replace, seals, valve


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