Backfiring

[dodges 3]

1991 318, 3spd. LA engine.

Hey gang. I've been trying to tack down the source of my backfiring, which came on, while at Van Nationals. It was mild then, once in awhile, but now, whenever I accelerate, it backfiries. It also backfiries when I pump the gas, while in park.

What I've done so far. Changed the plugs, air filter, PCV, checked and reset timing. I had previously reset the idle, which seems fine. I checked the transmissions throttle rod, which also seems fine.

Plans for today are to check the exhaust to see if there is blockage. I currently am not running the air pump, and have no cat. converter. Also I want to buy a compression tester.

Also, with regards to timing, my label says 10 degrees, is this the best setting, or should I consider a different one.

Any thoughts on this subject?? I thank you in advance... :help:

[charlie1935]

Time to check compression. :gr_patrio

[Dodgevanman]

I'm thinking maybe possible bad MAP sensor or TPS, but I'm not sure of the test procedures.

You didn't leave any empty beer cans down in there from the Nats did you? LOL!

[dodges 3]

Nope Nate, no empty beer cans from the Nats...When I was buying the other parts, I enquired about a MAP sensor, but they didn't have any in stock.

I have read at another forum, where having less then a quarter tank of gas can cause similar issues. As I recall, when I filled up leaving Cortland, it wasn't backfiring. I haven't yet refilled, as I haven't been driving it. I'm going to try that shortly, just waiting for laundry to finish. (joys of being single) Then I'm still going to pull exhaust off, and confirm no blockage. I'm concerned that maybe my Cherry Bomb got plugged, because of not running the air pump. And last but not least, prior to compression test, is to try diconnecting the EGR, as I also read that a faulty one can cause backfiring.

[dodges 3]

Tank is full now, actually got 15.5 mpg, with whatever problem I have. But it is still backfiring. Also tried disconnecting the EGR, which did nothing. Have a headache now, so I will do other checks later, or tomorrow.

[dodges 3]

Now I know what my problem is. It's all timing. Notr being satisified the way the timing was set, I was screwing around some more with it today, and I got it so it doesn't backfire. However, it does sound like it's dieseling, when I accelerate hard. Also, the timing marks don't line up at all. I mean I can't even see the mark on the damper. I'm going to screw around some more and try to get rid of this issue.

I just read this on ALLPAR, and I quote..."About the only problem with these engines was their "silent" timing gear and single-row chain which when worn causes a retarded cam. Replace it with a steel gear and double roller chain. You will know you have a retarded cam if you get backfiring through the carb on acceleration."

Does anybody know anything about this???

[Dodgevanman]

What is meant by "silent" is that the aluminum cam gear is coated in Nylon. Over time the nylon teeth break and could cause the timing chain to jump, but what mostly happens is that the chain stretches causing the timing to be off. Alot of slop in the chain and you'll never get the timing right.

[dodges 3]

Again, I thank you Nate. This appears to be the problem. I can't set it with a light, and I can't set it by feel, so it will be coming apart, in the near future. Looks like this years season might be over for me, we'll see. I've never done a timing chain before.

Does anybody have any pros, and cons with regards to using a gear drive, for the timing??

[landyacht318]

"Does anybody have any pros, and cons with regards to using a gear drive, for the timing??"

I once helped a buddy replace the camshaft in a SB chevy. He once had a chain break and ruin his engine. He's the kind of guy who has to have the best of everything and purchaced some type of "quiet" timing gears. When we would line up the marks on the crank and cam gears, we could not get the smaller 'figure 8' connected smaller gears to fit without moving the cam gear.

Anyway we had to install it ' 1 tooth over' thinking it was advanced and the engine never ran right. There was always a tapping from cyl#1 and no amount of rocker arm adjustment would help. The gears themselves were loud with a constant wah wah wah sound that got worse as it warmed up.

He was disgusted with it and drove it less than 200 miles in 18 months. When he finally decided to get it running right, he ripped the new cam out thinking it wasn't broke in correctly and had gone flat. He discovered that his stroker crank was hitting one of the CYL #1 lobes on his high lift Camshaft. I wasn't a witness to this second teardown, but he claimed that the '1 tooth over' alignment of the cam gears was definitely the cause of the contact. He put in a new cam with a slightly less lift, and a high quality roller chain for the timing and says it now runs better than ever. It's a school bus dually and he can smoke the tires in first. No tapping, no wah wah wah gear noise, and for a guy who I've never before heard admit to a mistake, claims that installing the timing gears was one of his biggest mistakes ever.

Don't know how this might relate to a mopar.

10 months ago, I replaced my own roller camshaft on my '89 318 and the new timing sprockets and chain (sealed power) I'd ordered looked crummy. Some teeth on the sprockets were chipped and the chain, in addition to being too short, felt sloppier than the one with 20 k miles on it. Unfortunately I was pressed for time and cash and had to reuse the old chain and sprockets.

I'd also not taken careful notes when I disassembled the front end and when reassembling, the RTV would go off (timing chain cover) before I'd gotten everything attached and tightened correctly. I wound up having to do a couple dry runs before making another attempt using the rtv. 12 k miles later and no oil leaks.

Hope this helps

[Dodgevanman]

First thing you want to do is get a good quality timing set. I personally recommend Cloyes. A double roller chain is nice, but not necessary. I also recommend this Fel-Pro gasket set and balancer repair sleeve.

Timing set Cloyes p/n C-3028X (heavy duty)

Repair sleeve p/n 16201

Gaskets p/n TCS65631

You'll need to drain the cooling system and block and probably remove the radiator to gain enough room to remove the crank pulley and balancer (you'll need a puller).

Pull the water pump (now is a good time to replace the pump, BTW) and timing cover. Before you pull the chain and gears off, you'll want to align the timing marks on the cam gear and crank gear (you may need to wipe the gears off so you can see the marks). Now you can break the cam gear bolt loose and pull the gear and chain off the cam. The crank gear is a pain in the butt to get off. Generally you can use two large screw drivers on each side behind the gear and "walk" it off the crankshaft, but if it's seized you can use a little bit of heat from a propane soldering torch (no oxy-acetlene!) to expand the gear and it may slide right off.

Now you can put everything back together. Just make sure your gasket surfaces are nice and clean and don't forget to replace the front seal in the timing cover...it comes in the gasket kit. The repair sleeve slides over the "nose" of the balancer and gives the front seal a nice smooth surface to ride on. I generally use a small piece of 2x4 to tap the sleeve on. Be careful when you do this since the metal is thin.

You'll notice the timing set comes with the front part of an oil pan gasket. It's pretty self explanatory, but you can use a bit of RTV to help seal this area. Since you'll be working near the pan, and may possible get exess coolant or whatever down in the pan, I recommend changing the oil as well. I always do.

[dodges 3]

Excellent advice Nate. I will look into those parts, and part #'s here in Canada. Looks like this overtime cheque is history. Ohwell. Do it all now, and not worry about it later. Thanks again Nate.

[Dodgevanman]

I don't recommend a gear drive for a stock application although you could use it, but they are very noisey....whine like a supercharger.

[dodges 3]

I'm starting to think that my van might be off the road now, until next spring. And I may end up pulling my engine, soon, while it's still warm. Then I can clean up under hood, and prep for paint, as it's not the same color as the exterior of van. And then during the winter, get my 318 rebuilt, and buy all new exhaust, and whatnot, for spring installation. This way I will no longer fear those long trips to VANNIN'S. I guess if I go to anymore this year, it will be in my 2000 Caravan.

[dodges 3]

Oh also, is it possible to just unbolt the front frame and pull engine that way?? Kinda slide it out from under the van. I do realize that a bunch of other stuff would have to be disconnected, but it seems easier this way.

[van-nut]

I don't see why not. I bet that's how they were put together going down the assembly line. I have also been contemplating doing the same thing, sooner or later - pulling the engine and and giving it a major go thru - not really a rebuild, per say, but all new seals, gaskets, timing chain, water pump, Hughes plenum, major internal de-sludge (had the valve covers off once, not pretty), maybe roller rockers, etc, etc, etc.

Mine sure looks like the engine cradle, engine, trans, and lower A-arm assys will drop right out the bottom. I did a FWD car like that once and it was no worse than up thru the top. If I ever do mine I'll post lots of pics. Runs great and only one or 2 very minor leaks right now, but like I said, sooner or later. 123K miles now and so far so good. :D

Pete

[Mad Joe]

last time I had a similar problen, my timing chained had slipped, but of course mine would not run.

[B-300]

The gear drives are noisy... My brother had one on his A-100 van and the noise was loudest in frint of it since it echoed thru the under-tray in front of the radiator.
It also required drilling and tapping the block for an aditional bolt... We replaced it with an Edelbrock double roller which can't be heard and has +4 and - 4 degree settings to allow tuning if you want. The 0 setting was correct for the came in his case and I used the same in my van, and it is also set at the 0 setting to degree the cam correctly.

[dodges 3]

Thanks B-300. I have already dismissed the idea of a gear drive. I'm going to start hunting down parts tomorrow.

[87318]

would bad manifold gaskets cause it to backfire? my 87 did not backfire until i had dual exhaust put on it.

[dodges 3]

Not sure. Right now I have it all torn apart. I didn't get the damper off yet. Thats for tomorrow. Then I'll be cleaning and detailing, everything under hood. Then wed. I'll be putting it back together, with new (reman) waterpump, and new thermostat. Check out some pics. of my progress.

[Dodgevanman]

Ewwwwwwwww! I would degrease that puppy before I went any further. Ewwwwwwwww!

:)

[dodges 3]

It doesn't look as bad now, with the damper and timing cover off. I still have to pull the crank gear, and clean off the old gasket. But it was obvious that the chain had skipped a tooth. This pic shows the marks off, just a bit, but from here rotataing will make them further off.

[dodges 3]

To continue with this thread, please goto my Year in Progress Thread. Thank You.