'87 Suburban, help diagnose engine problems (long)

it could be as simple as the drain-back holes in the heads being plugged up

oil will pool around the two rear valves' stems, and no seal will hold it when submerged

this was a huge problem on the early 4.3's in cars

I had this problem when I put the long block in my Blazer. Turns out the TBI unit I borrowed from a van hadn't been in the greatest shape, and the injectors where leaking. An irregular pattern from them will cause the fluctuations on O2. You might want to pull the air cleaner and have a good look at the pattern. Look for a lot of dribbles straight down from one or both of the injectors. Sometimes a timing light helps to get a good look at the pattern, but it's not necessary. As Gary pointed out, fuel delivery may be a problem. Have the fuel pressure tested, since it will let you know the pump, filter, and regulator are doing their job in one fell swoop. Of course, changing the fuel filter first might be a good idea, especially if the mileage on it is unknown, as in this case.

Lastly, If you end up thinking the engine needs major work, pull off a valve cover and I'll bet you find the valve stem seals are shot. For very little money, replacing these can solve many oil burn issues. Most noticeable in the two rear plugs being sootier than the others, but not necessarily wet. Have you got any numbers on your oil consumption, and is it leaking anywhere?

IIRC = "If I Recall Correctly" and he's referring to the A.I.R (Air Injection Reaction) pump(s).

-Bret

[I]f [I] [R]emember [C]orrectly

Ya see, since I'm not looking at this particular vehicle, I have to go off of memory. Being from Wisconsin and winters being what they are here with road salt, most of these shit boxes went to the boneyard years ago.

Duh. Would A.I.R (air injection reactor) have been clearer to you? (doubt it)

That's deep, very, very deep.

Was there theoretical rocket science in my reply? On air pump equiped engines, the air from the pump is diverted to the exhaust manifolds (exhaust ports actually) during cold engine operation to assist in reducing the pollutants after a cold start-up. Once the engine is warmed up sufficiently, or in this case, goes into closed loop fuel control, the air from the air pump is diverted to either the catalytic convertor or to the air cleaner housing (to muffle). It's not a great feat of logic that air being pumped into the exhaust ahead of the O2 sensor(s) when it shouldn't be is going to create a false lean indication to the ECM and the resultant rich mixture command by the ECM.

The real beauty is that it costs absolutely nothing to check to see if this is the cause of the erratic engine operation. Simply disconnect the air pumps temporarily and test drive the vehicle to see if the condition (code 44 with sooted plugs) returns.

Neil;

It appears that we may be wasting our time on this one.

Regards,

G

shiden_kai wrote:

Hm. I did ask the guy what these numbers *should* be. No answer. I would like to know, eg, what they should look like in a new 454 engine.

Una

Gary, I believe you're right!

Hell I live in the Great White North, with copus amount of salt, and around here we oil spray every year to keep rust at bay. My 89 astro's body is as pristine as the day I bought it and it is now at 350,000 km with original tranny and motor and still running strong and burning no oil.

I'm not talking about my personal vehicle(s).

I can only exert influence on a small portion of the 3 million or so vehicles running around on Wisconsin roads.

Maybe thats why no one knows how to fix them?

Kinda like you? you mean?

dubious,

So do I!

Hatt

chrome, what is this "oil spray" all about?

Hatt

mechanic

No denying that Ian, but I'm not as stupid as I was anymore.

Hatt

No one? That's an awful lot of people. [snip]

Yeah? maybe? like? me?

Used to see a lot of people doing this. You basically pop off panels and wash out the crud, then spray motor oil or trans fluid into the body cavities like you were doing undercoating but it doesn't dry out. Then you wait till it finishes dripping out and spray under the body as well and inside the frame rails. Done every 6 months to a year it will really keep the rust away. I also know at least one person who also wipes down the entire body with oil but I think that is a bit too far.

The technology has moved on from the days of using motor oil or tranny fluid. In canada we have two franchises, crown and rust check that that use specially formulated oils designed specifically for rust proofing. Along with them there many independent shops using various concotions. The system I use is from a body shop I know. The use a thicker gel type oil spray on the undercarriage and thin oil in the panels. The oils are special mixtures used on ships and rigs in marine enviroments where special oils sprays for corrosion control (as you can imaging, salt water is a tough enviroment) are very common. Very powerful stuff. The best out there. I do it before every winter.

The other dimension to body preservation is external paint care. This envolves checking for paint chips and sealing them (clear nail polish for small one is great, body shop for major ones), and waxing with high quality wax twice a year, once before the summer and once before the winter.

My brother is into the same maintence (also very frequent oil, tranny, power, diff etc fluid changes ) as me and he has an 87 astro with 750,000 km with only a tranny rebuild at 500,000 along with some front end renewal, the roads are hell around here) and the van looks like new and the motor is still in decent shape. Not bad for a vechicle driven year round in winter climes with lots of salt.

We both drive astros, with corvettes (2003 convertibles) for second cars. It is amazing the money you save when you drive an easy and cheap to maintain vechicle for decades.

Sun, oscillescope 21, 2003, 1:21am (CDT+5) From: snipped-for-privacy@att.net (Una)

I used the Suburban today to tow somewhere, and on the way back through Glorieta Pass and later on the flat the engine sounded wrong (stuttering?), had poor power, and sometimes exhausted thin black smoke.

I followed up with both shops. Shop #1 say they read the codes off the computer, and told me the mechanic's name. I still have to talk to him, to find out what else he did in the 2 hours he looked at it.

At Shop #2 I talked at length to the mechanic who did the work (not the guy who called to sell me a new engine).

His findings:

The O2 sensor is detecting huge instantaneous fluctuations in the exhaust, from extremely rich to extremely lean and back again. This looks like oil is confusing the O2 sensor, which gives the TBI instructions to adjust the air/fuel mix. And there is a lot of soot in the tailpipes. So there may be some usage of engine oil, but when there is, it is being masked by excess fuel, hence when there is visible exhaust it is black (not blue).

Compression test finds poor compression and suggests rings are bad: Left =A0 =A0 Right dry wet dry wet

119 142 129 149 Front 123 139 131 151 127 141 131 144 127 141 131 149 Rear

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Una, Humor me.......... unplug the transmissions "lockup solenoid" connector on the drivers side of the tranny case. Square plug. Then drive the truck, when you get a chance, under the same conditions.

Scrib Abell ~~lugs the keg up the stairs to get it closer to his recliner........~~

utilized for it's intended purpose, the following is a vengfull tool.............

the easiest way to get a job done..................is to get the shop braggart to "show" you how to do it..................and look astonished when he's through...............

. (after proclaiming the benefits of diagnosing all situations "from the inside out".......) snipped-for-privacy@lycosSPAM.com (DJ=A0Hatt) "DJ Hatt" added this for his closing statement.......

but as I said, I spent thousands going around the outside of my motor, and listening to every other mechanic call the next a liar. ....

(prompted this reply from.....)

"shiden_kai"

This only proves that stupid customers come in a close second to stupid mechanics.

Ian =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

No denying that Ian, but I'm not as stupid as I was anymore.

Hatt =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

Ian, does that mean he doesn't diagnose flat tires from the inside out anymore?

jest curious.........

Scrib Abell