My exhaust manifold is leaking around the shaft for the heated air valve. Is there any way to fix this w/o pulling the manifold? The valve is working fine. I know it's leaking at the shafft because I could feel it.

Also, would this make my engine idle poorly? I'm still having troubles with that.


Thanks,

Joe

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Joe Hoppe

71 D100 225 Super Six 727 AT on 2008 Crown Vic CopCar frame

64 Valiant Wagon 225 904 AT 3:23 8.75"

The leak won't make your engine idle poorly unless the leak is so bad that it is allowing so much exhaust back into the intake that it is acting like an EGR valve.

I would check for vacuum leaks, valve lash, ignition timing, points, plugs, cap, rotor, curb idle mixture, idle speed.

If the leak at the heat riser valve shaft is large enough for you to detect by sound and/or feel, that makes it very large indeed. The later exhaust manifolds (with the approx. 2-1/2" round cast metal heat riser valve counterweight, not the earlier 1" x 1-1/2" rectangular sheetmetal counterweight) have replaceable bushings that are (naturally) larger in diameter than the valve shaft. If one or both of the bushings works loose -- which is probably what's causing your leak -- then yeah, you're going to need to pull the manifold and put a manifold heat control valve kit in it.

And yes, a large exhaust leak like this in that location most certainly *can* cause poor idling, for it means exhaust is probably getting sucked into the intake tract via the air cleaner. If you kept the thermostatic air cleaner setup (with the flex duct running down to the sheetmetal shroud arond the center part of the exhaust manifold) then exhaust *IS* getting into the intake tract via the air cleaner.

Being in Texas, I would just pull it out and plug the holes with some short bolts. If your choke is set up properly, you will not have any cold drivability problems. I did this to my engine and have never had it die when it was cold, even in the winter with snow on the ground. Of course, this might not work in colder climates.

Reed, Dan, Eric;

Thanks. I seem to have cured the problem, temporarily at least, with a correctly sized washer and some JB Weld. Hopefully that will work.

Reed, I've done all that you suggested, and the engine is rebuilt. Has a Pertronix ignition. Looked at the plugs and they're uniformly a nice light brown. Lash has been done, etc. etc. Carb is a BBD, and has been rebuilt and all has been adjusted to the best of my ability.

It is running better now, but still very difficult with "cold" starts. It was in the 50s this morning. Choke seems fine, vacuum pull-off is adjusted, and the counter weight moves as the engine heats up.

Dan--I'm running an aftermarket open air cleaner with a K&N filter. So I doubt I was getting that exhaust leak directly.

Maybe the air filter is contributing to my cold runnng problems? It is just a little rough now when it is warmed up.

Everybody's expertise is always appreciated,

Joe

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Joe Hoppe

71 D100 225 Super Six 727 AT on 2008 Crown Vic CopCar frame

64 Valiant Wagon 225 904 AT 3:23 8.75"

Eric: No, wrong, bad idea. Texas has nothing to do with it. Plugging the holes with bolts means full-time exhaust heat to the intake manifold, which is why you've "experienced no cold driveability problems", but which results in poor running and poor fuel economy when the engine is hot. Jiggering the valve so it's always in the heat-off position, on the other hand, results in poor running and poor fuel economy and extra engine wear (via oil dilution) when the engine is cold. That valve is there for a reason, and everything works a lot better when it's working properly. Crappy hacks like shoving bolts in holes is OK for clunkers that should've been in the junkyard 5 years ago -- not for a vehicle that's actually driven.

Joe: An open-element air cleaner is definitely not the right thing to use. Worst of all possible worlds: You get cold air (and, in your case, leaked exhaust) when the engine's cold and you want warmed air. You get barbecue-hot engine compartment air (and, in your case, leaked exhaust) when the engine's warm and you want ducted cold air. Put the Super Six air cleaner assembly back on, complete with all cold and hot air ducting and with the vacuum motor hooked up properly. And use a proper OEM-type element; a K&N does not improve power, fuel economy or anything else, and lets a great deal more abrasive dust into your engine.

The JB weld will not take the heat for a long term fix, find some high temp. glue / sealer made for stoves, heaters, etc. and that may hold-up.

Better to try to fix the worn / missing bushing.
I had one of the bushings fall-out of the rear wall of the manifold and I was able to tap-in a replacement without pulling-off the manifold. I used a short "sleeve" of pipe as my installation tool to push the new bushing over the shaft and to "press" it into the casting's bore.

If it is the front bushing that is leaking then you need to pull the manifold off. I don't know of a way to get that pressed-on counter weight off without bending / removing the flapper valve inside the manifold.
DD

Doc, great idea on using a piece of pipe as a driver for a new rear bushing! Joe (and everyone) if you do this, disconnect the battery negative cable first, so your pipe or hammer doesn't hit the starter terminals, starter relay, etc. and cause sparks and heat and a possible fire.

Just another observation: Forget the stereotype: It CAN get pretty cold in Texas, certainly enough to cause driveability issues. Even way down there in the Hill Country.
Like they say up in the Texas Panhandle when a blue norther comes in: There ain't nothing between here and the North pole but a barbed-wire fence!

You make me laugh. My car is a daily driver, gets 20+ MPG on long trips, around 15 in town. Its called fine tuning like tuning the carb and adjusting the timeing curve in the distributer. Ask Reed, Ksteb or anybody else who have seen my car.....its a far cry from a clunker. Sorry Dan, your not the only one who can make a car run properly.

Eric, I never suggested I'm the only one who can make a car run properly. And your 15/20mpg is nice, but with a properly-operating manifold heat control valve you'd do better. That's just how it works. Cramming bolts in the heat riser valve shaft holes isn't the same as recurving a distributor or rejetting a carburetor -- not even close. It's more like shoving a rag in the gas filler to replace the gas cap. It works, kinda, sorta, but not really.

Doc-- Where can I find a bushing? Anybody? Does anyone have dimensions?

Also Dan, I've never had the right air cleaner. My 71 truck came with the single barrel carb, so I've always had the open air cleaner.

K&N has such a good rep--do they really just let a lot of extra crap through?

Does the old style snorkle-less air cleaner help at all--or is it no different from runnin an open element?

This is getting to be quite the lively discussion!

Joe

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Joe Hoppe

71 D100 225 Super Six 727 AT on 2008 Crown Vic CopCar frame

64 Valiant Wagon 225 904 AT 3:23 8.75"

The bushings are sold as a part of the manifold heat control valve repair kit, which last I checked was still available from the dealer -- Don't remember the part number, but you can just ask for a manifold heat control valve repair kit for a 1985 Dodge D100 with a 3.7 litre engine.

It'll be worth your effort to find and get the right air cleaner. Those hot and cold snorkels were put on there for a reason, and the Super Six 2bbl carb is calibrated on the assumption that the thermostatic air cleaner will be present and working.

The old-style non-snorkel air cleaner is not better, the only reason to run it is if a year-correct appearance is needed on a pre-'70 vehicle (or if you want to make an unsilenced air cleaner so you can hear the "WONNNNNNNNNNNNNNNNNNNNNN!" every time you stomp the gas...)

K&N does not have a "good reputation", they have a well-paid marketing department -- just like Slick 50 engine goop or PIAA lights. Everyone's got an opinion; facts can be found at http://www.bobistheoilguy.com/airfilter/airtest3.htm and at http://tinyurl.com/4lu2y. I like this quote from the first URL: "stock OEM type filters perform very well in filtration and don't inhibit flow nearly as much as some think."

Thanks, Dan. Good links. I guess I'll be going back to paper. Now to track down a snorkel type aircleaner housing.

I'm always learning stuff on this site.


Joe

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Joe Hoppe

71 D100 225 Super Six 727 AT on 2008 Crown Vic CopCar frame

64 Valiant Wagon 225 904 AT 3:23 8.75"

In TX you ought to have plenty of good W-yards to work from...go make a daytrip of it and have lunch at Kreuz' Market! (You do know about Kreuz', right?)

If no luck locally, http://www.car-part.com searchable used auto parts nationwide.