Whew... I fixed the cam access plate on the head. That sealed the oil leak and that one vacuum leak. I then discovered the freq valve wasn't buzzing. That was simply a contact in the RPM relay that was out of adjustment. A tweak with a needlenose fixed it. As soon as the valve had power, my idle shot sky high. Adjusting the CO screw didn't really bring it down much. It either stalls or still revs too high. I took a quick second w/the carb spray and discovered that all six injector seals leak. Could this be responsible for the crazy idle? I now noticed the engine was pretty warm. The guage was approaching 220 so I took a moment to bleed the cooling system. I get periods of fluid and periods of air. I'm not sure yet if I got all the air out. I'm not blowing coolant anywhere. This is good. Now I noticed the dang cooling fans didn't kick on. I have a new otterstat but I tested the connection to make sure I had things wired right and I think it may be bad. This is not good. However, the temp gauge dropped way back down as soon as I bled the cooling system. Now, I have a concern...after a while, the engine seemed to get pretty warm again, but the guage never went anywhere near that high again. Can I trust this thing or not? I'm not keen about blowing the engine up again after all I did to get it back together. Opinions? Rich #5335 --- In DMCForum@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> wrote: > Vacuum leaks are indeed idle (low RPM) problem. And Martin G is > correct -- fuel mixture gets adjusted rich to compensate, which then > haunts you at higher RPM's (where leaks go away). That's why vacuum > leaks are MPG killers. > > Find them methodically anywhere air can enter engine OTHER than > metering device (air sensor plate). On most engines this is limited to > single piece intake manifold and a few vacuum hoses. PRV is different. > Breathes internally to a degree I've never seen before. Means you're > going to check things not normally sources of vacuum leaks, like valve > covers and oil pans. Note also upper air assembly alone has as many > mating surfaces as rest of block. > > Start by isolating engine from rest of car. Can have a vacuum leak at > far end of a hose, like power brake booster or A/C mode switch. No > DeLo vacuum operated accessories are needed at idle, so simply > disconnect hoses and plug nipples. You'll hear instantly if leak goes > away (which then requires one by one analysis to find bad accessory or > connecting hose). > > To find leaks on engine itself, I like to use aerosol products with > pin point spray straw. Private label carburetor cleaner is only 78 > cents at Wally World, so it's become my solvent of choice. Is > flammable, however, so use judiciously. Ensure ignition isn't arcing. > Electric motor cleaner isn't flammable but is about 3X more expensive. > Push button and straw can be transferred to can of whatever if it > doesn't come with. You can also make a flex extension for straw from > tiny size vacuum hose to reach backside of engine, under intake > manifold, etc. > > If solvent hits area that is vacuum tight, is no effect on idle. > > If solvent hits minor leak, RPM's increase momentarily as solvent > seals it. Gets sucked into engine of course, so effect is temporary. > > If solvent hits major leak, RPM's drag as it is sucked into engine as > fast as you can spray. > > Started diagnosis on my PRV at the top: Fuel distributor wasn't > totally tight against upper air assembly. Simply snugging down removed > that leak. > > Working down, found leaks where U pipes mate to upper air assembly, > where cold start tube mates to intake, and in most fuel injector > seals. Intake manifold itself leaked around #5 cylinder. Had biggest > leak of all in passenger valve cover caused by slightly uneven match > of timing chain cover to head. Am currently mulling over prospect of > removing crankshaft pully to reach leak in timing chain cover seal > (hey Rich, can I come visit your impact wrench...) > > Is longer prospect than simply setting off a smoke bomb next to car to > see where it goes. Take it one step at a time and you'll eventually > find them all. Don't forget to carry diagnosis all the way down to oil > pan -- PRV can have vacuum leak there too. > > Bill Robertson > #5939 > > >--- In DMCForum@xxxxxxxxxxxxxxx, "jamesrguk" <James_rg@xxxx> wrote: > > Hi list, > > > > My car idles like a dog and I want to fully check for vacuum leaks, > > I get a good reading of the vacuum gauge when connected to the > > intake manifold. > > > > However when I pull the rubber plug out (the one that sits above the > > mixture adjustment screw on the metering head) and put my finger on > > it I can't feel/hear any suction? the car runs, all be it badly, and > > the idle is terrible. > > > > What is the best thing to spray around the engine bay to detect > > vacuum leaks? > > > > Rgds > > > > James Yahoo! 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