Ran compression today . Can anyone please tell me what these readings mean . 85 fiero SE V6 80,000 miles
(you more experienced people unlike me ) Thanks PFF member "lurker" for the information on how to run the check .

Check an engine manual or Google the minimum engine compression for the v6, also, normally, all cylinders should be within 10% of the others.

i am trying to check and see why it smokes when i start it up . What else could i check and can i do anything about it .

Smoke on startup is usually valve guide seals, IIRC...

[This message has been edited by twentyeight (edited 07-11-2004).]

Do you have the rest of the numbers? Especially the wet numbers for the other four cylinders? From the looks of it you've got a ring problem on number five. Startup smoke is commonly caused by worn out or hardened intake valve stem seals, which are relatively easy to replace on the car, but the ring problem on five may be more serious.

JazzMan

depending on how much money you have and how badly you want your car to run t its best, your numbers arent too awfully bad.

as stated above, it appears you have low compression on several cylinders, esp 2, 5 and 6. the dry/wet difference on #5 definitely implies a worn ring problem, and smoke on startup is usually valve guide seals.

the seals can be fixed either on or off the car. i know rings can be replaced in the car on a duke, i dont know about the 6.

get the rest of the wet (oil) numbers, particularly for 2 and 6, and get back to us. you may need to pull your heads and look at the condition of the gaskets, pistons and cylinder bores before you decide to go further on the rings.

[This message has been edited by lurker (edited 07-12-2004).]

Compression test interpretation:

from dry test:
- if two adjacent cylinders have a low reading, check head gasket
- if pressure builds up erratically, possible burned valve seats or sticking guides

from wet test:
- if compression increases to nearly normal, the rings, piston and cylinder need service
- if pressure does not increase, the valves are the problem

Tim

I had to give up and did not do any more compression tests . my arm was burnt , and fingers dead. now that the engine has cooled off .. i guess i cant test it again (unless i put all the plugs back in and heat it up)
So if i did not want to do a costly repair (as i cant take it apart) would it help to use one of these .. oil Additives ??
STP Smoke Treatment
STP® Engine Stop Leak
etc.

thanks all you guess for your help
Mickey_Moose, lurker, JazzMan, twentyeight, 88 Formula + for you.

yes, the oil additives might help as a temporary solution. your compression figures aren't all that bad that you can't drive it for a while, and the initial complaint, smoking on startup, can be fixed fairly cheaply. do you own a shop manual and basic tools?

quote Originally posted by lurker: yes, the oil additives might help as a temporary solution. your compression figures aren't all that bad that you can't drive it for a while, and the initial complaint, smoking on startup, can be fixed fairly cheaply. do you own a shop manual and basic tools?

yes i do have basic shop tools . i have the service manual , and i have the haynes manual . So to stop the smoke i need to change the intake valve stem seals / valve guide seals? just so i know exactly what to ask the mechanic .. or ask myself and look it up to see what i have to do . ?
thanks!

quote Originally posted by bsculptor: yes i do have basic shop tools . i have the service manual , and i have the haynes manual . So to stop the smoke i need to change the intake valve stem seals / valve guide seals? just so i know exactly what to ask the mechanic .. or ask myself and look it up to see what i have to do . ? thanks!

yes, that's correct, you need to change the seals on the valve guides. what is happening is that oil is leaking past the old ones and getting sucked into the combustion chamber, where it burns off on startup.

there are a couple of ways to approach this. some auto parts stores will loan (with a deposit) the spring compression tools. it's not rocket science. at the very least you'll need to pull the valve cover. if you leave the heads on the engine, there's a tool that compresses the valve springs, but it's a bit more complex, you have to keep the valves from falling into the cylinder when you release the spring tension. youre going to have to check your manual and see if you feel comfortable doing this.

if you pull the heads, there's a different tool you can use to compress the springs, and you dont need to worry about dropping the valves, but of course pulling the heads can be unpleasant.

my 4 cylinder has this problem, smoke on startup. maybe i'll give this procedure a shot in the next couple of days and let you know how it goes.

Just a quick note, I did the valve seals on my 84 2.5L.

I had the same problem, smoke at startup and after idling for a while say at a stop light, big puff when you take off.

I did the seals with the head on the engine.

I pulled the valve cover to do the seals, found that the 84 2.5L only has seals on the intake valves.

Visible slop side to side on all the valve stems from wear.

I did replace the intake seals, not much noticable improvement on the smoke issue.

I'll live with it till it's time for a rebuild.

My .02

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Where will the road take you today?

If you are just looking for something to dump into the engine that may help, I heard 'Engine Restore' is suppose to work fairly well (at least that is apparently what a fair number of used car lots use).

Tim

The rings may very likely be stuck due to carbon build up. It's worth it to try this procedure. Remove all of the plugs and pour about 1 oz of Seafoam or other decarbonizer into each cyl. Wait a few days if possible, then spin the engine over to remove the seafoam and reinstall the plugs. Next slowly pour a can of Seafoam into the throttle body on a warm engine as you fluctuate the rpm. Do it outside because it will be quite smokey. good luck

Phil

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86 GT TTops, 3.4 Auto.....bought from Doug of Fiero Warehouse

GM auto tech for 27 years. Specializing in electrical and computer problems. I will never be able to return as an auto tech again. I get EXTREME satisfaction helping others and will go to Extreme levels to help you if you need help. I have LOTS of free time on my hands. This forum and the help I give, allow me to have a purposeful life. Bring on the problems......LOL.

quote Originally posted by fierohoho: Just a quick note, I did the valve seals on my 84 2.5L. I had the same problem, smoke at startup and after idling for a while say at a stop light, big puff when you take off. I did the seals with the head on the engine. I pulled the valve cover to do the seals, found that the 84 2.5L only has seals on the intake valves. Visible slop side to side on all the valve stems from wear. I did replace the intake seals, not much noticable improvement on the smoke issue. I'll live with it till it's time for a rebuild. My .02

Did you replace the square section seals under the keepers, down inside the spring retainer? All the valves have those. Of course, if you're getting side to side movement on the stems that's pretty badly worn out. Want a set of oversize stem valves for that, already ground?

JazzMan