[MLB]

After I bought the car, an early inspection of the engine compartment revealed soot where the engine block meets exhaust manifold at cylinder 4 (back of engine). I thought there must be a leak in the manifold gasket, will look into that before summer, and before the 9 hr drive to Parade in Traverse City.



Its in the shop now for clutch/flywheel replacement (wow, badly worn, I think POs did not know how to drive a clutch, because I'll be putting in the 3rd one!)

Anyway, with the front of the exhaust out, I can look up into the manifold, and the port from cylinders 1,4 is black with soot, but the 2,3 port is clean and silver.



So, a couple things I'm considering:

1) probably is a manifold gasket leak at cyl 4.

2) could the soot inside 1,4 exhaust be telltale of a dirty injector? and do these engines have independent injector control, or are they all set to inject the same? I'm considering just sending all injectors out for clean&flow test. Pelican has a crazy price for new ($637 each, but Marren only $95, I would consider buying a new set of injectors for $400, even if only for spares)



Anything else I'm missing?

Thanks!

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[MB968]

When I did my engine rebuild I noticed soot also where the exh. manifold meets the head when I was reinstalling it in the car. It wasn't on all cylinders; pretty sure it was around #4 like yours. I found that the nuts on some of the exh manifold studs were not all as tight. Snugged them all up to the approx. same torque (don't think I could get a torque wrench on them). Since then I've checked the area when under the car, and looks like snugging up the nuts fixed the small leak. Bottom line, check the nuts first, you may find like mine that some are not as tight as they should be.



I think it is highly unlikely that what you see is a result of injector issues. But, pull your plugs. If some cylinders are running too rich you will see it in the plugs.

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[flash]

re injectors:



the OEM injectors are actually no longer available from anybody but porsche. bosch cancelled them with no replacement. pelican gets them from porsche. they are only in germany. there are a little over 130 of the last time i checked. they are insanely expensive.



marren is selling rebuilt ones for that price, and when they find out that there are few new ones left, and are that expensive, i anticipate the price jumping.

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[Lear35A]

There are numerous places that test/rebuild/balance flow injectors. It's not that expensive. Unless you drop a big rock on one of your injectors I can't imagine having to buy new ones.

FWIW, I had mine done @ www.injector-rehab.com

And I agree, the first step should be getting a socket on the nuts that hold the manifold in place and check the torque as best you can.

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[tamathumper]

Now that I've taken them out to install Supercharger Stage 3, I looked into getting my OEM ones cleaned, but the web site said to not have them cleaned unless they were going to be re-installed within 30 days,... so what to do with them? They've been sitting for a little while now, and I can't imagine that's good for them either?

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[flash]

not sure why anybody would say that, unless they were hoping to sell you injectors later. it's bad advice. who was that? i'll be sure not to do business with them.



letting them sit with gunk on them is a sure fire way to have them end up permanently damaged.



how long do you think they sit on the shelf before being sold? while there is a chance that there could be stuff still in there, and it might gum things up, to be safe, you should have them cleaned now, and then again if they are to be installed. that's exactly what i am doing and why.

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[MB968]

Should you need to service injectors, check out these guys in Cincinnati and Lousiville: http://dieselinjectionservice.co/index.html



Got to know the guy who ran the Cinti operation. Was impressed at how he ran the operation; later was surprised to find that he had and MBA, not typical of someone running a small shop. Found out through him that there is quite a large service business for diesels. Most of their business was for commercial trucks, but also worked on injectors, turbos, etc for cars. Had the injectors for my Mazda cleaned and flow tested there.



You might check your local area for a similar diesel service shop.

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[tamathumper]

The advice to use injectors within 30 days was on Witch Hunter Performance, at http://witchhunter.com/shipinfo1.php



"It is advised that you install and use injectors within 30 days after you receive them back to minimize any chance of them sticking. If you don't plan on using the injectors for a long time, it may be best to wait before sending them in. If they do have to sit for extended periods, don't allow them to dry out and store them in a plastic bag or airtight container and store indoors."

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[flash]

while it is true that in a perfect world you don't want them sitting, what they say tells me that you get what you pay for with them. they probably just do a sonic cleaning, and don't actually take them apart and clean the parts and change things. i know the 944 guys love them, but it's always about the price with those guys.



i use RC Engineering because i know how they do the job. i get before and after flow charts too. when i had mine done, the said they had no worries about them sitting for a year, especially if i put them in air tight baggies. if i were to let them sit for many years, i might want to clean them again, and i probably will, just as a precaution.

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[Cloud9...68]

Hmmm... So what about people like me who spent over two years working on an ambitous project on their cars? I kept them in a (definitely not air-tight) box in the garage while I was working on the car. Sounds like I ought to have them sent out to be cleaned and balanced. I hope I didn't screw them up. Sure wish I had known this (and about fifty other things) before I started my project...

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[MB968]

Waiting to have them done just prior to use is probably not bad advice. I suspect they are suggesting this just to minimize the risk that they might stick. That being said, I suspect it is a rarely followed advice with few people having issues with sticking injectors. Personally I'd wait until I was in a reasonable window of their use to have them cleaned/flow checked.



And, Cloud, with all you've done, it is cheap insurance to have them cleaned/flow tested before you get your car on the road again. Why take the chance. The cost isn't that much compared to all you've invested in terms of time/$'s. And, here is one added reliability benefit.



For anyone that gets the injectors flow tested, I'd suggest that you install them in reverse order of their flow amounts; injector with the most flow closest to the pressure regulator end of the fuel rail, down to the one with the least flow at the opposite end of the rail. There shouldn't be much difference between the flow rates, but they will likely vary from one injector to the other. In theory, the whole fuel rail has the same pressure, but in practice there is likely to be a very minute change from one end to the other (ever so slightly higher at the inlet end and lower at the pressure regulator end). This is especially true at the rpm and load conditions where you're closest to max. flow of the injectors. So, you can balance a little bit by installing them as I mention with a little less risk of one cylinder running leaner than others.

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[flash]

they SHOULD NOT sit dirty, whether in a bag or not. the varnish and such that gets in there can permanently damage the injectors. store them clean ONLY. yes, this MAY mean having to clean them twice, depending on how they were stored and how long they say, but it's still a lot less expensive than buying new ones. i've seen plenty of injectors put on the shelf dirty and ignored, only to find them beyond repair as a direct result of it.

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[MB968]

Seems to run counter to all the guys that buy bigger injectors for their builds out of donor cars in a junk yard. Or the guys that have a stable of cars and only take them out a time or two per year.

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[flash]

not at all. those guys just don't know any better. guys who buy stuff like that from junkyards deserve the headaches they get. more often than not, it's just plain stupid, and they just haven't learned better yet. you don't buy operating parts from junk yards, and expect them to work without rebuilding. you buy body parts and such, if you absolutely have to (i won't buy anything from a junk yard unless it flat isn't available anywhere else), but never injectors and such. basically, if the yard won't warranty it, don't buy it. otherwise, you get what you get.



as for guys with stables, every collector maintenance company will tell you that you must run the car at LEAST once every 3 months to keep the injectors working properly. even the gas in the tank has to be refreshed regularly or it turns to varnish.

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[Cloud9...68]

Sigh... Wish somebody had told me this when I started my project - never occurred to me to clean my injectors before storing them. Crap, there I go whining again...



What are some symptoms of "bad" injectors? Once I got past my no-spark problem, the engine fired after just a couple of cranks, which I thought was borderline amazing for an engine that was taken down to the bare block, and hadn't run for two years. It idles smoothly, and, although I've only driven it a few miles, and very cautiously (no insurance, long expired registration, and no seat belts at the time), the engine feels VERY willing and strong beyond even my loftiest expectations.

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[flash]

fuel smell, rough idle, lack of top end, knock sensors engaging, uneven exhaust temps - those are a few

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[KRAG50]

Plugs or a plug that shows signe of lean or rich.

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[Cloud9...68]

OK, I'll keep an eye out for those symptoms, once I start driving it again. But my initial impressions are that I don't have any of them at the moment. I did do a Run-Rite treatment about a year before the start of the rebuild, and I was very diligent about always using fuel system cleaner (a top-secret, special blend concocted by a guy in the business of engine oil analysis for about 30 years), so the injectors should have been very clean when I took them out.

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[tamathumper]

I just spoke to the guy at RC Engineering specifically about this. He said if I have them cleaned now and then store them, I should make sure they "click" before installing them by using something like a 9V battery across the terminals. I ordered a cleaning and will ship them out tonight.

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[flash]

those guys are the best

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