Hello there, im new to the forum. I have a 2002 ford ranger 3.0 with 182k. I recently purchased this truck with the check engine light on. Previous owner just got new plugs, distributor on the truck several months ago. Test drive was great so I expected something simple as far as why the CEL was on. Took it to get code scan at autozone, told me it was a cylinder 6 misfire. That lead me to take it to a local mechanic that told me cylinder 6 had low compression. Of course they recommended I pay them $1200 to year my engine apart.

The truck runs a little rough at idle, motor shakes a bit...and sometimes CEL will flash at idle but not while driving. It misses just a little at idle but not when driving. The engine shake kind of seems like an air leak, but I havent came across an actual leaky hose. This truck uses no oil, gets normal gas mileage and doesnt leak anything. It actually runs pretty decent. It shows no loss of power or any of the symptoms you usually find with a loss of compression. My question to you guys, (keeping in mind im not very mechanically inclined) is..what should I do next? Is it safe to drive this truck with what I told you guys?

 

You don't happen to have the compression number do you ?
eg. 120 psi/100/or 140 ???

EDIT:
There is also this, but according to Ron, your truck does not fall into the years where the valve seat problem occurred.
However maybe someone replaced the heads with the problem valve seats, do have any history of it ?

https://www.ranger-forums.com/genera...nk-2-a-149357/

You can check for vacuum leaks with a spray can of starting fluid too, that may also explain the low compression.
When it's running spray it around the upper intake manifold by #6.
If the idle increases there may be a vacuum leak in the upper intake manifold gasket.

 

I dont have any numbers.

 

Do you understand about any of the things that I talked about (terminology) or in the link to the other thread ?
Are you able to pull the plug out of #6 and post a photo of it ?
Do you know how to take a compression test ?
A tester is around 30 bucks.

 

I understand most of it. I have almost no tools which is becoming a problem. Ive watched videos on how to do compression tests. Im also going to talk to my mechanic tommorow and ask specifically what they did to test the cylinder.

 

If you're here for help that means that you are going to do the work yourself, so you will need some tools.
That or a mechanic will have to do the work.
Once we (and the forum)know the compression numbers, that will be a big help.

 

If someone wanted 1200 bucks to deal with a low compression number, they probably will be pulling the heads off for that amount.

 

Mechanic said it was at 25psi and would barely move while cranking. Im shocked because this truck runs great. He also said the compression goes back up when you rev the engine. Said it seems like a burnt valve and there's no ranger in driving it except I might start to burn oil

 

Wow !
25 psi is low, burnt valve seems odd, but not unheard of I suppose.
If the valve was burnt, 99% of the time you can hear it in the exhaust on the compression stroke _ it sounds like a bad miss, but yet you say it runs great.

If this was my truck I would be pulling the heads off.

EDIT:
Read your first post again, you said it runs rough at idle and it sounds like there is an air leak.
So yeah, probably a burnt valve _ time for a rebuild on the heads.
Most here find it cheaper and easier for a set of reconditioned ones.

 

At idle engine shakes a little, and misses a bit. While driving it runs great

 

With only 25 psi it would shake and misfire.
Thought of another thing that could be the problem and this would cause a burnt valve and that would be varnished up lifters.
If the previous owners didn't change the oil regularly, the lifters get dirty and new oil doesn't get inside them.
They get stuck in one position and as the valve wears it can't come in contact with the seat anymore.
When this happens the valve can't dissipate the heat properly and the valve burns.

Mine was heading in this direction, the oil was changed and no new oil was inside the lifters, just this thick black molasses goop.

So if you do decide to have someone fix this, before pulling the heads off, once the lower intake manifold is removed, pull the lifters apart on the cylinder with the low compression and take a look _ do the intake as well, but more then likely it will be the exhaust that is the problem.
My lifters were so dirty I couldn't them apart until I heated them up with an acetylene torch.

Eventually you'll have to make a decision to learn to do it your self, have someone do it or live with it, but if it is a lifter problem, it will only get worse by affecting other valves, assuming that is the problem.

 

Would seafoam or engine restore help my truck at all? My mechanic said because while driving that the compression goes back up, so therew no harm in driving it as is..except I may start to burn some oil in the future.

Please understand im not very mechanically inclined. I can do basic stuff to vehicles and know a little bit.

 

I know you're not mechanically inclined, but I just say it like it is.
I'm not a big fan of Sea Foam, it's more of a preventative thing then a fix, but it couldn't hurt, but don't expect miracles, it won't happen _ just don't do what I did and hydro lock the engine.

Having taken my engine right apart, I can say with out a doubt that Sea Foam did absolutely nothing in removing serious carbon deposits.
I will also say that if you have gummed up lifters that it will do nothing for that either.

And your mechanic is right, the compression will go up while driving.
That happens because the engine is simply running faster and it doesn't have time for the compression to leak down.

It's not going to hurt anything to drive it this way, but I know it would really bug me, especially the annoying CEL blinking all the time.

I don't know how busy you are or what your financial situation is, but when my dad taught mechanics in high school, night classes were offered and there were many others long out of high school that enrolled in the mechanics classes with the regular students as an extended learning program set up by the school board and the ministry of education.
This is here in Canada though, so I don't know what the situation is like in Iowa.

Speaking honestly though, are you the type that no matter how hard you try, you can't put something back together ?
My dad called that machine sense, having a natural feel for all things mechanical, either operating or repairing things.

 

Im good at putting things back together, lol. And luckily the CEL only flashes after it's been at idle for around 10 minutes. Never flashes when driving.

 

another ol school trick is drain a quart of oil and either "add a quart of tranny fluid or a quart of marvel mystery oil"

i like the marvel mystery better my self !