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Can someone please advise:
I know a but about mechanics but not been in the trade for years:
I'm just replacing the accelerator pump diagphragm on the carb (Motorcraft 4 barrel)
I notice the two rear barrels on the engine base have some kind of tarnish or carbon build up in the barrels and I heard that it might only be using 2 barrels?? Now I was a mecahnic in the coal mines for year but I'm not auto guy.
Can this or does this make sense?
Its an older RV and I plan to takre her cross country, 1985 with 43K and I've driven her about 1000 miles. The RV runs pretty good albeit 5mpg as expected. I know I was losing gas on the perished diagphragm.
If the old girl starts to become too much of a $$$ investment (I paid $2600) then sorry she's going to the knackers yard so I'm hoping to limit the amount I put into it.
Does the build up in the rear two barrels indicate any serious threat?
I am replacing the vacuum hoses etc. Hoping not to do a rebuild if the bus runs. 5mpg is already budgeted in my expense.
Thanks for your time folks
Cheers
Alan
What you're describing is "varnish" and pretty common in old carbs. It's a sign of cheap gas and/or running slightly rich. It isn't necessarily a problem, but it could indicate a vacuum leak if the secondaries are opened with a vacuum diaphragm instead of a linkage.
Once you get the hoses replaced, you'd be doing yourself a favor if you'd check for vacuum leaks with a can of Gumout while the engine is running. If there aren't any leaks, you don't need to worry about a rebuild. If your carb is sitting on a bakalite spacer it is pretty typical for the gasket above and below to leak after a few years, but this is pretty easy to find and doesn't call for a rebuild. If you find a leak in the air horn (the top plate of the carb) and main body this means a rebuild.
email Alan Andrews
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