1996 Saturn SL2 Questioning cause of EGR valve failure afte

Looking at the service invoices - here is what they say was done:

1st Visit: along with a 150k mile service pkg and an injector cleaning - leaking coolant - "Found head gasket leaking. Tech removed cylinder head and sent it out to be checked and resurfaced. Reinstalled head and verified no leaks now". Also, "tech verified and found oil leaking on belt - needs valve cover gasket and belt - tech replaced valve cover gasket and drive belt"

Note: prior to this, the engine had been using oil slowly - had to put in a quart every 4 or 5 fills. I hadn't noticed any leaks so I assume it was burning it.

2nd Visit: pretty significant oil leak noticed within a week. "Found valve cover ASM warped, replaced valve cover ASM".

Should they have noticed this the 1st time around - or am I expecting too much?

3rd Visit: (loss of power, flashing SES light - had to tow). I forgot to mention that the problem didn't occur in the shop. They tried driving around and stressing the engine after arriving, but SES was out and didn't reoccur apparently. "Tech hooked up scan tool, found code P1406-EGR valve sticking, P0133-front oxygen sensor. Needs new DCR valve+oxygen sensor).

I didn't have them repair it at this time. Later, after the car was cold, the SES came on again, but is not flashing. I've been warming up the engine before driving the last couple of days - no flashing, but SES on.

So - what do you think - should I shell out another $500 this further repair? Do they have further culpability? Or is it just an inconvenient coincidence? I can't afford to keep paying for the next failure in the cascade.

Another thought, is this replacement something I can do myself. I used to do my own tuneups & brake work about 25 yrs ago before things got "too" complicated. If it doesn't require a lift or any big part removal, it might be worth my time to save half that cost.

Thank again.

So, it sounds like they "may" have been the cause of the 2nd failure (over tightening the valve cover). That would seem to fit - in that it was unclear to be how they could miss the amount of oil leakage in the shop after the repair. I imagine that a warp might within a short time, and might not cause an immediate problem. Sigh. Can't prove it, so I guess that's money lost.

As to the 3rd problem - the SES light has gone off again on it's own. I think I'll let it go for a while and see what happens. If it returns, I'll attempt to replace it myself. I'm not sure what I'm looking for, and not sure if I should sign up for one of the online repair manuals (though, still would be cheaper than taking the car in for repair if I don't screw it up). I suspect I could identify it after getting a replacement part ok.

Thank you much.

Ok - I replaced the EGR valve, but problem still occurred. The old EGR did look fairly well gunked up, so probably a good think anyway.

Something else to note: The problem only seems to occur if the engine is cold and I drive up a significant hill (from home, I drive only a close freeway which slopes up for a couple of miles - that's consisistently when the SES comes on and starts running rough).

The SES goes off on it's own after a couple of trips, though those are almost always avoiding that long hill. If I warm up the engine first (let it idle for 10 minutes), the problem doesn't occur even on the hill.

Anyway, I put in new oxygen sensor (the old one really didn't look bad - some carbon ringing the sensor round the insert hole, but otherwise just the gray dusting and no clogging.

So, I took the car to a parts place to look at the SES code - 1 code: P0300 - "Random Multiple Cylinder Misfire Detected"

I'm wondering if the timing could be off? Would they have screwed with the timing chain while replacing the head or the valve cover? If so, could this have been the problem all along - that is, marginal firing causing the EGR and/or Oxy Sensor to flag a problem first?

Another possibility - when I went in the first time, I did have them do a 150k service - which included new plugs. I suppose one of the them could be marginal, though I wouldn't imagine that would cause misfires, rather just plain failures to fire.

What to do you think?

Thanks again

Sigh. I finally subscribed to the on-line service manual to get specs. Reading thru it appears the timing is not adjustable, so no procedure to check that I could find, apparently. Also, to check the timing chain requires removing quite a bit of stuff just to examine - more than I'm able to attempt. However, the problem may be getting worse. SES seems to be coming on more often - though the weather has gotten cold and rainy as well - so it may just take longer to warm up.

Tomorrow I'll pull the plugs and visually check - simple thing to do anyway. I think I'll head back to the parts store and recheck the codes - just to see if anything has changed.

Any other ideas? Thanks again for the help.

I've checked the codes a couple of times. 1st time was only p0300 (random or multiple cylinder misfire detected). 2nd time both p0300 and p0301 (cylinder 1 misfire detected).

The service manual seems to indicate that the SES condition occurs after a threshold is reached. And they want you to connect and see if it's occurring while running. The store says that requires a different computer.

I tried checking plugs, but was rudely surprise to find that it requires a very long and thin socket to reach the plugs. Guess it's back to the store again.

Thanks

You should disconnect the battery cables to "reset" the computer since you've replace an electrical part on your engine.

Just disconnect battery wait for about one/two minutes. Then reconnect the battery and see if that don't help ya.

I took the car back to a car parts place and the last code is the same as before P0300 - "Random Multiple Cylinder Misfire Detected". However, there is a 2nd code this time - P0301 - misfire in cyl 1.

I wasn't able to reach the plugs with my sockets, so I bought a t-handle remover and checked the plugs. I found that 3 out of 4 plugs were only finger tight, and the 1st plug had a rubber boot over it (looks like the protective boot from an old sparkplug socket). Has a hole for the plug pin so the wire was still able to connect.

Without completely removing the plugs - I blew out the holes to remove any debris, and scrubbed off the plugs. The insulators and arm were clean - but the metel rim was coated in a black and shiny spotted coating - didn't look like oil, but something else. So, I took a wire brush to it.

(My only concern is that it leaves the insulators gray, and I don't know if the residual metal is an issue).

I reinstalled the plug (has washers - so finger tight then 1/2 turn - about as far as I could physically do with a T-handle anyway).

I thought this was clearly the problem and it was nailed, but on a test drive the SES came on under the same conditions. I haven't been able to get back to the parts store and check the code again yet, but I suspect they are the same.

Sorry - I missed the 2nd page of responses till I saw mine missing. To answer these last two:

1st) The plug wires measure for cyls
1 = 6k (24in)
2 = 5k (20in)
3 = 4.5k (16in)
4 = 6k (12in)
plus probably some extra for the long boot down into the cover (about 4 in I think)

2nd) I had disconnected the battery when replacing the EGR and Oxy Sensor. Haven't since then, so disconnected for good measure. I haven't been able to drive it yet, but will shortly and let you know if it changes anything. I don't suspect it will.

Thanks again.

Did some more diagnosis - seems to only indicate what it ain't.

1) I've checked the vaccum, which appears fine.
2) Can't easily check compression - my compression gauge is about 30 year's old and won't fit this engine.
3) A week after cleaning the plugs, I notice they are fouled again (black on the ring, though the insulator is ok). True for all the plugs. I assume it's the misfire causing this.
4) The behavior isn't so much firing at the wrong time, but more like not firing at all sometimes.
5) Checked coil secondary resistance which is what is expected.
6) Checked spark with a spark tester. THIS is interesting. At 30k volts I get a consistent spark. But, at 36k volts, it starts out ok, then within about 10 seconds, almost completely disappears. The service manual doesn't give an expected voltage that I can find, but the spark tester indicates to use 36k for the GM electronic distributor. Not sure how what to think of that.

I'd appreciate any further thoughts. Not sure how to interprete the spark test. The service guide moves on to fuel pressure and injector tests. I don't have a fuel pressure gauge, may have to invest some more.

I think the parts store is tired of me coming in a borrowing their scanner (without buying anything)- maybe time to invest in one of the those.

Thanks again.