Greetings all and may I say how happy I am to find this great website! I was referred by Daniel Stern via the Mopar newsgroups. First let me say that I grew up in a Mopar family with my father having a '68 Hemi Cuda and a '70 E Body Style Challenger. Mom drove the kids around in a little Dart. But the Dark had a 340 and could definitely be described as one of those "granny creepers" which generally won a lot of Friday night street drags.

Presently my Mopar experience is not quite as exciting but I recently bought a 1986 short wheelbase Dodge passenger van with a slant six. I bought this van about six months ago. I am currently stumped
on a proper diagnosis concerning engine problems I just started experiencing. I am not that great at diagnosing problems but with a point in the right direction I can generally fix the problem without defaulting to a $65 per hour mechanic. I am trying to squeeze as much life out of the van that I can before needing a rebuild. I am pretty broke lately and a rebuild is going to cost a couple thousand
dollars. This because I do not want to try and replace a van motor in my backyard. On this model van, the entire front end has to be removed in order to yank the motor.

Okay, so we all know that slant six motors run forever. And I need this van for work. So again I need to keep her going until I can afford a rebuild. And hopefully this will
be a while. The motor only has 122,321 miles on it. The previous owner was a retired military officer who used the van to take his family to church on Sundays. And he bought the van from the dealership in 1986. So this van has not seen any hard
miles.

Symptom #1 ...
Starting a few months ago the van starting loosing major
power. It felt like a loss of compression. It takes quite a while to accelerate
up to a reasonable highway speed of 65 miles per hour. The entire acceleration
is slow and noisy. Sounds and feels like the van is bogged down in mud. Then eventually
the transmission hits its cruise range and the van runs fine.

Symptom #2 ...
About a month past the van started skipping and jerking when I cruised over 45 miles per hour. The van would not do this in short spurts or city traffic. Only on highway
trips where the van motor maintained speeds over 45 miles per hour for long periods of time. The jerking symptom felt as if the van suddenly lost all gas and air. As if the motor was completely choked. This occurred for a second or two at a
time and the van would only do this once or twice during an entire trip.

Recently I drove from Atlanta, Georgia down to New Orleans Louisiana. The van did this
jerking symptom twice during the entire round trip which was several hundreds of miles. The van made the trip and got reasonable gas mileage considering that a little slant six is pulling a huge van chassis. I eventually replaced the fuel filter but stil;l get the jerk synptom.

After this recent trip weird
stuff started happening. I pulled the shroud from around the motor to inspect the carb and this is when I noticed that I had a pretty bad valve cover leak. After all, this is an old vehicle with the original factory gaskets. This is when I started to fear that I may have a bad head gasket.

Symptom #3 ...
As I was inspecting the motor at a glance I removed the air cleaner cover to look at the carb. Upon
removing the cleaner I noticed small traces of oil in the bottom of the air cleaner cover. Yikes! Right? Am I right in guessing that a bad head gasket causes a lot of the problems I have been experiencing? Wouldn't a bad head gasket cause major vacuum leaks resulting in a loss of power? Also, wouldn't a blown head gasket
splatter oil into unusual places? The reason I am posting my diagnosis problems here is because I am mentally stumped and a mechanic buddy of mine told me motor problem was probably as simple as a bad PCV valve. I find it hard to believe that a bad PCV valve could cause the multiple symptoms I am experiencing.
And if the head gasket is bad, I figure I might as well get the entire motor rebuilt. Because the labor to change out a head gasket on a van is nearly as much as dumping
a new motor. Why spend $600 or more on a head gasket that may only extend the life of the van for a little longer when $800 labor will get me a new motor installed.
For the record, I found a rebuilt slant six with a year warranty for $974.00.

Well, thanks again for your time. Hopefully someone can help point me in the right directiont.

Sincerely,
Jake

I doubt that it's your head gasket. I would just give it a tune-up. Spark plugs, spark plug wires, distributor cap, rotor, PCV, air filter and a couple of cans of carburater cleaner. You should be able to do all of this for about $50. See if you can borrow a timing light and check the timing. Check for any obvious vacuum leaks and make sure that the heat riser valve in the exhaust manifold moves freely. You should also adjust you mechanical lifters. Do a search on the procedure. Doug has covered that a few times (valve adjustment).

After you do the tune up, and it stills does that same thing. I would check the catalitict converts to see if they are plugged up.

I agree with Bob, time for a good tune-up and check to see if you get spark advance as RPMs increase.

Let's see, if this is an 86 SL6 engine then it has hydralic lifters so no valve adjustment is needed (or possible)but you can check the torque on the head if you have the valve cover off. I do not think it's a head gasket problem but if it is, the head bolts will have lost torque, so that is a clue.

The plugged exhaust is also a good possibility so check for a plugged cat. converter.

I bet it has something to do with the ignition system. Does this Van have a Lean Burn system?
DD

Is that a manual or automatic trans?
What ignition setup do you have? Federal with ESA?

I agree with the advice given, probably not a head gasket but a major tuneup is indicated. After new wires, plugs, cap and rotor, etc, I would:
1. Check all vacuum hoses for brittleness and cracks. Probably time to replace all vacuum hoses anyway. Any other vacuum leaks?
2. Use a vacuum gauge to check idle vacuum, steadiness,adjust mixture. Then rev it to see if the vacuum drops, indicating clogged converter. (Try it without EGR, which will lower vacuum when engine is revved.)
3. Check timing, should be 12 BTDC at idle and 33 or so at 2500 RPM and 16 incles vacuum on the ESA sensor. If you are not getting advance, then it is time to troubleshoot the ESA, which I assume you have.
4. All that oil in the air cleaner/carb and leaky valve gasket is blowby, kinda normal on a old engine that is pushing a van around. Replace the valve cover gasket, PCV valve and hose, clean the breather. Be sure to keep the oil changed and maybe try something to clean up the rings. It sounds like you get in some long highway miles, so things shouldn't be too gunked up and carboned out. For some reason my 1987 van with 199K miles is thriving on Arco gasohol.

Good luck, let us know what happens
Fred

Oops, I forgot about those newfangled Slants with hydraulic lifters.

Oil in the air cleaner housing will either be a plugged PCV or breather, or rings. For the power loss/jerking, have you replaced the fuel filter lately?

_________________
Official Cookie and Mater Tormentor.

I would also dump some 91% alcohol or fuel drier in the gas tank. Water in the tank could cause your "bucking".

_________________
Chuck Rivers, Webmaster

Sounds to me like fuel starving, since she does it only at highway speeds.
Check your fuel pump too.

Rafa

I have the same problem with my truck. Sounds like a fuel delivery problem. Maybe a weak fuel pump(or possibly bad fuel pump eccentric). Use finger to see how strong the vacuum is on the inlet side of the fuel pump. Maybe a plugged fuel line. Or posibly a loose or leaking fuel hose or fuel line on the vacuum side of the fuel pump. Possibly plugged fuel sock on the end of the tank pickup.
Heat can also aggravate the situation! Insulate fuel lines from sources of excessive heat.

_________________
'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Check (and replace) the short pieces of rubber fuel line. One by the fuel pump the other by the fuel tank.
$1 worth of rubber hose cost me a $65 tow bill.

3 things make a motor run..

fuel (fuel itself, fuel pump/lines, carburettor)
spark (distributor, leads, plugs, timing)
mechanics (pistons, rings, bores)


Basically, it really sounds as if you need to tune the thing.
If I pulled off 2 spark leads, to the untrained ears it would sound like
the motor is ready for the scrap heap.. put the leads back on and it
runs like a dream.

Your symptoms sound like a classic case of 'just needs a tune'
After that many years you must definatly (as other people have already stated) do:


Plugs
Leads
Distributor cap
check timing and advance are working


Clean/rebuild the carby
Clear out the fuel tank with some addative
Check the fuel pump (or just throw in a cheap electric pump)

Change the oil/filter
Check for vacuum leaks in hoses
Change air cleaner if it needs it
PCV valve

If it blows blue smoke then it's rings, otherwise she's got 1000's of miles
left in her.