Rough idle need second opinion

[McKnightContracting]

My 99 Chevy Tahoe just recently started to ride and idle rough, so i took her too a mechanic to see what was the issue.. They told me that i needed a whole new engine and was going to cost me over $5k. Well unfortunently i dont have $5k and the truck is a 99 and isnt worth that much to start with. LOL. It is low on miles, for the year with approx. 190k.
The mechanic told me my cylinders should be putting out around 250 psi??? (could be wrong with the verbage) and that ALL 8 of my cylinders were only putting out around 45.. My question is, is it possible for all of them to just fail at once, and is there ANY other route i can take to fix her?
I have only taken it to one place and havnt got a second opinion, but was pretty shocked at what they said and havnt done much with it since.. Its sitting in the driveway with me being scared to drive it for almost 2 months now..
They did tell me that my radiator had some sort of brown sludge type stuff in it, and that a few of my plugs were burned pretty bad..
To me it just seems weird that all of a sudden i have a blown engine when it was driving so well for such a long time.
I am new to this forum and this is my first actual post.I have read and got plenty of advice over the years by reading what you guys have said about other issues on here, that i thought i should give it a shot and see what i come up with as far as advice on here.. Thank you in advance for whatever light you guys could shed on my unfortunent situation im in..:happy160:

 

[Tex99Tahoe]

Yeah, that's some screwy info you got there. 150 psi is about right for a good engine, 45 psi probably won't run at all. Brown stuff in radiator? BarsLeak in there? Plugs burned pretty bad? Did you replace them, or did they just put the old ones back in? If so, no wonder it's running bad. I just replaced mine, looked like they've been in there forever. These usually run so well that it's easy to neglect proper servicing.

I take it you're not a gearhead, and dependant on the auto shops for the work. What you got was what a gearhead would call 'the runaround' and 'selling you work you don't need'. On the other hand, if you're not into auto maintenance, and your time is more valuable in your job/profession, then a fresh engine is the practical approach. But, as you said above, that is more than the book value of the truck. So, a viable alternative would be to put the $5000 engine money with a possible $3000 sales price of the truck, and buy a later model runner...

 

[McKnightContracting]

No im definently not a gear head.. Im actually a 20 year construction worker so im not an idiot suit..lol But, that being said, i dont know much about vehicles and auto mechanics either.
Now that i think about it, yes they just stuck the plugs back in and i never replaced or checked them.. Ive thought about doing it multiple times, but to be honest i was so upset with the diagnosis that i didnt feel it was worth it..
As far as the sludge, i did check and it is slightly sludgey. What would cause that?
Do you have any ideas on what to do besides the buying a new truck, or replacing engine idea? lol.. Any ideas on what is going on, or what i should check? How to fix it or ideas on what to check into?
Thanks again for your reply. Im new to here, first day, and not sure how this whole post,reply thing even works..
Thanks

 

[Tex99Tahoe]

You're doin' fine, these forums are really handy email-like collaborations, where everybody/anybody can read/learn or jump in to offer advise.

Your best first action would probably be to catch-up on all the maintenance/tune-up stuff. Change those plugs for sure, inspect/change other ignition stuff. If it runs better after that, then it could be saved. Then do the OBD scan, flush the cooling system, and put some money/time into those maintanance things that will help prevent early failures, like lube/grease.

 

[lesterl]

Sludge in the radiator, could be oil, blown head gaskets could do this..... This wouldnt be a deal breaker either...... Compression guage can be a cheap buy, about as easy to use as replacing a spark plug, pick one up at your local Harbour Freight and retest it, the engine should not run at all below around 100 PSI, and 45 it wont fire.

Get a gauge and check it .... Could be the best $20 you spent....

 

[McKnightContracting]

OK.. I went ahead and replaced all the plugs. They old plugs didnt look as bad as i was expecting (the way the mechanics made me think they looked, all burned out) and it still idles rough. It does however feel like it runs alittle better, which could definently be my imagination from not being in it for awhile. I rechecked the radiator and it seems to me to be more of a rust kind of sludgy issue.. Theres still water in it,and was full, but the cap seems to have alot of rusty gunk on it. I bought some radiator flush and im going to do that soon. I dont think however that would affect the actual idle issue, right?
Do you have any other suggestions on what to do next?
Im definently going to Harbor freight and buying one of those guages, but just wondering if theres any other ideas.
Oh, and changing those plugs was a pain in my ass..lol.. Not much room to move on those back couple with that metal covering stuff in the way..lol.. Plus i must be an idiot, because i almost killed myself getting the actual plug wires off the plugs.. lol.. Those things stick on tight..
Anyway, thanks again VERY much for the help..

 

[McKnightContracting]

I went on a few other posts around the forum and thought i found out something that might help.. I believe my cat conv are bad.. Both.. There is a rattle under my truck and ive been told by a few people that my cats are bad.. Would this cause an idle issue and if so, can you just bypass them, or do you actually need them? I was told you could do without them. Thanks again.. :waytogo:

 

[lesterl]

Cats are just for emissions, if you dont have testing they have been hollowed out in the past........

 

[Tex99Tahoe]

Lesterl mentioned head gasket. You might check for this by looking for bubbles at the radiator cap neck opening.

Whatcha do is remove the radiator cap, fill the radiator to the very top of the neck with water, start the truck, watch for bubbles to emerge from the water in the neck, add water as necessary to keep the water high in the neck.

First couple minutes of bubbles can be ignored as the system warms-up, after which shouldn't get any bubbles.

But, if bubbles continue to emerge over a 10 minute period, you may have a blown head gasket, and that could make the coolant dirty lookin'.

 

[McKnightContracting]

Im going to try that this evening, thank you very much. Is there anyway to bypass the cats or anyway to get rid of that raddling? If i dont need them here in Florida because they dont do emissions tests, then i should be able to just get rid or bypass them, right?
Again, please forgive my stupidity.. Im sure these are elementary questions im asking, but im learning alot. Thanks.:smiley-face-popcorn

 

[amtronic1]

Take it somewhere else! Get a second opinion before pissing away your money.

 

[lesterl]

can get a replacement cat pretty cheap also....

 

[McKnightContracting]

OK.. I did the radiator bubble trick, and there was no bubbles. I suppose thats a good thing that i dont have a blown head gasket, right? Are there any other ideas of what to try next? Im getting to the point were im going to sell it, and i dont want too. I would much rather have it running and be my wheels for the next couple years.. Please help.. Thanks

 

[Tex99Tahoe]

Good, no bubbles.

I suppose the next thing would be the shotgun approach, that is replacing those things most likely needing service or replacement. First would be the distributor cap and rotor. Then, sparkplug wires. Then fuel system cleaner.

You could get a better idea of what's wrong by doing an OBD scan. Some auto parts stores offer a free scan, helps them sell parts. AAmco offers a free diagnostic, mostly for transmission work, but could help shed light on this.

Diagnosing rough running maladies is a difficult task for non-gearheads, there are so many things involved that even experienced mechanics can find it challenging. Getting more hands-on shop opinions is invaluable. Being able to fix it yourself is very economical and rewarding, but you must prepare yourself for the mountain of knowledge to be acquired, and the difficult work involved. Even then, sometimes it's a crapshoot, fixing multiple things that needed fixing anyway only to find that it's really a worn/blown engine.

You might get lucky and find it's only a bad distributor cap, like another member here discovered. So, you need to decide if you're willing to chance that doing all the overdue maintenance work will yield a good running truck, or get rid of it. There's a fair chance that you'll be putting a lot of time and money into this before identifying the problem, and that problem could involve work beyond your facilities (special tools, equipment, experience). That's why the hands-on and OBD diagnostics are strongly recommended.

You could pull the distributor cap and rotor, and inspect, that costs nothing. But do you know what to look for? There's possible microcracks, carbon tracks, rotor tip and contact wear/pitting/corrosion, excess gap, misalignment, ...etc. Simply replacing them eliminates the inspection chore, but that costs money. This scenario can happen in multiple areas, ignition system, O2 sensors, fuel injectors, computer controls, egr system.

Well, enough rambling, hope I haven't scared you off. Just want you to understand how involved this can get if you're willing to pursue this on your own. Another member here recently documented his efforts to solve a misfiring issue, which eventually led to a complete teardown and rebuild of the entire intake manifold system (with good pictures too).

 

[rockenthebowtie]

If you had blown head gaskets you would be loosing coolant and it would be overheating... catalytic converters would not cause a misfire.. check compression if all cylinders are with in plus or minus 15 psi your engine is fine you mentioned that you changed the spark plugs but did you change the plug wires distributor cap and rotor ? Also another common failure is the CPI fuel injectors assy under the upper intake manifold... they have a tendency of plugging up and cant be flushed out and need to be replaced

 

[Jimmert]

Your 99 tahoe has 4 o2 sensors on it, 2 before each cat and 2 after. They communicate with on board computer and let it know what the fuel ratios need to be. If you remove the cats it will run very rich. Replacing the cats is a very easy replacement that you could definitely do yourself if you have some common tools and some want to. It's just bolts holding it in. You'll only need the new cats and I would replace the 2 upstream o2 sensors as well as the 2 downstream ones.

 

[lesterl]

Old post. Removing Cats wont make run rich (mine doesnt have any that function any more.) If you are running rich, replacing the cats will just burn the new ones up untill you fix the rich condition. On an older rig, the bolts are probably rotten/ rusted badly....