how to diagnose a vehicle has unknown problem?

[rrb6699]

I inherited 2005 Mercury Mariner with unknown problem. besides that its been sitting about 3 yrs.

where do I start after I check to see if engine is not frozen? it was abandoned in his yard after a problem I don't know about. I assume it wouldn't run.

I'm getting a battery, gonna squirt marvel oil in the plugs. my bet is electrical or brain issue but I have nothing to go on. its high mileage I'm sure so ill guess over 250,000.

any help appreciated.

rr

[aleekat]

You need 4 things. Compression, fuel, spark and spark at the right time.

Edit: I wouldn't use the battery the 1st time to try and turn it over. Pull all the plugs, squirt some penetrating oil and let it sit. Then I would turn it over by hand.

[rrb6699]

Originally Posted by aleekat

. I wouldn't use the battery the 1st time to try and turn it over. Pull all the plugs, squirt some penetrating oil and let it sit. Then I would turn it over by hand.

engine turns over by hand ok. gonna try a battery next, but can't use one in my primary vehicle. I'll have to get one.

the reason I asked about the brain or timing was bcause if that is the problem will I be beating my head against the wall? I can check the timing marks at least by removing the timing cover this has a 3.0 V6 in it.

thx,
rr

[aleekat]

You have already assumed what is wrong. Without proper diagnosis you're just guessing. All good mechanics I have known start with the "what is working" and do a process of elimination to determine what is not. Have you considered the engine is good and the tranny is toast?

[rrb6699]

understand. I'm just trying to anticipate things that will hinder the normal diagnosis process.

just trying to find out what maybe have checked first if possible. I just want to start the engine. I will worry about tranny after that.

update.
Just today (now) I found out from a relative that the vehicle started running erratically then kept stalling. eventually, they couldn't start it at all.

rr

[aleekat]

Then I would check for spark 1st, the simplest.

[rrb6699]

sorry, will update once I get a battery. hopefully, this week.

[Bharatarora]

Listen to the engine's noise carefully and if you still cannot diagnose the problem then I suggest that you should head to the nearest service station.

Thanks

[aleekat]

Originally Posted by Bharatarora

Listen to the engine's noise carefully and if you still cannot diagnose the problem then I suggest that you should head to the nearest service station.

He hasn't got it started yet.

[rrb6699]

ok, had minor issues like a hurricane (Irma) basically hit me dead on with the eye where I live. I managed without power for 9 days and now have a battery to start diagnosing the Mariner.

I will post what happens when I turn the key, if it turns over at all - ill check for spark.

we can go from there. still doin some clean-up. I'll do the start test in the next few days.

[aleekat]

Glad to hear you are okay. The car can wait...