[sector95]

There may be something else....I'm not familiar with your particular emissions controls but typically the EGR valve is controlled by vacuum (in the pre-computer engines). When the engine is cold the EGR system does not function. Once the engine reaches a certain tempurature, the EGR valve will begin to operate. There should be some type of vacuum switching valve that is screwed into the block and able to sense coolant tempurature...it might have several vacuum lines plugged into it as it probably controls the distributor vacuum advance also.

If this were my truck, I would definitly replace the EGR valve (they are not that expensive...30 bucks maybe... and relatively easy to swap out). In addition to the erroding pintle, they can become carbon fouled which can keep the valve from seating correctly. I would replace the PCV valve and any crankcase breather filters (usually attached to the air cleaner). I would go through and replace *all* the vacuum lines with new ones as they are probably rotted, cracked and leaking; this will cause all sorts of problems. Another cause of grief on older smog engines is a plugged or restricted catalytic converter. If the cat is bad then it can also affect how the EGR system operates.....if it were my truck I'd replace it....besides, the old GM monolithic cats are very restrictive even when they were new. NAPA should be able to set you up with a replacement cat (this will be a little pricey....maybe a bit over a hundred bucks....check on their website napa.com or check the AutoZone website, autozone.com, also). I had to do this (and more) on an '85 S10 w/140K and once I was done, it ran like a top and passed its emissions check with flying colors.

It all just depends on how much money (is it worth the cost?) and what you have to do (pass emissions?) to get it on the road....

Good luck

Mike
98Sierra