88 Dakota 3.9 issue

I know from my Haynes manual that there are marks inside on the crank
and cam gears, but that is not something I want to disassemble to get
to. Lets see... PS pump, alternator, smog pump, water pump all need
to come off.... Not something I want to undertake casually.

As to how I know what stroke my piston is at, I was at TDC on the
exhaust stroke, since my distributor was 180 out from number 1. It's
got to be one or the other, either TDC at on the compression stroke
with distributor pointed at #1, or as I found it...

Now, that doesn't mean I couldn't be just one tooth off, which could
probably prevent starting. After I validate that I've got proper gas
flow to the carb, the next step would be to pull off the valve cover
on one side and observe how the valves are situated when they come up
on TDC of the exhaust stroke...

On Nov 4, 5:03*pm, "rob" > wrote:
> your timing mark for the crank might be inside on the crank gear, right
> where the chain goes on. *that's the way it is on the 3.5 but not sure on
> the 3.9L
>
> I'd be curious to know what stroke your piston was on when it came up. did
> you have a valve cover off to verify the valves were closed or open on the
> exhaust side?
>
> "bruce" > wrote in message
>
> ...
> On Oct 23, 2:37 pm, Steve > wrote:
>
>
>
> > bruce wrote:
> > > My88Dakota3.9 quit yesterday, and I had to drag it home. It had
> > > begun running rough and would only go if I kept the throttle mostly
> > > open, then it quit. Based on what I saw when I was troubleshooting,
> > > I've begun to wonder if it could have skipped a tooth on the timing
> > > chain. The motor has 140K on it, but hasn't been a problem up to
> > > now...
>
> > > I checked the cap and rotor, and there was a fair amount of wear on
> > > the contacts, so I replaced them. I checked for spark and have that.
> > > It smells gassy when I crank it, and it cranked faster than normal.
> > > Knowing that it had spark, and apparently gas, I shot it with some
> > > ether while cranking and it didn't catch at all. I know that the
> > > distributor is turning because it had changed position when I popped
> > > the cap off. To top it all off, the starter wasn't engaging
> > > reliably. Are there any timing marks that are external to the
> > > engine? Are there any other common problems that can cause this sort
> > > of thing?
>
> > It does sound like a timing jump. An883.9 is probably like a pre-92
> > 318 in having a plastic-coated "silent" cam gear, which sheds its
> > plastic coating and lets the chain go slack enough t0 jump time
> > *eventually. If you haven't touched the distributor other than changing
> > the cap and rotor, check your timing with a timing light while having a
> > helper crank the engine. If the timing chain slipped, the distributor
> > timing will also be way off and that's a dead giveaway. You can, of
> > course, set the ignition timing back to the correct point by turning the
> > distributor, but the valve timing will still be wrong and it won't run.-
> > Hide quoted text -
>
> > - Show quoted text -
>
> Well, I don't think it looks like a jumped timing chain. *The motor
> has no external timing marks on the crank anywhere that I can see, so
> I pulled the number one plug, and felt the piston rise to TDC as I
> turned the motor. *The Rotor was pointed 180 out from #1 on the
> distributor, so that would appear to be good...
>
> I know we've got spark because I pulled the coil wire out and had good
> strong spark evident. *Rotor is turning.... *Next I guess I'll look at
> a fuel filter.

bruce wrote:
> I know from my Haynes manual that there are marks inside on the crank
> and cam gears, but that is not something I want to disassemble to get
> to. Lets see... PS pump, alternator, smog pump, water pump all need
> to come off.... Not something I want to undertake casually.
>

Its not that bad, really.

But you should still find the slot on the harmonic balancer and make
sure it aligns within a few degrees of the O degree mark on the timing
cover. You'll have to clean away some dirt and grime to find them, but
given that this is an 88 carbureted 3.8, the whole front of the engine
should look EXACTLY like an '88 318 v8.