Having a problem

[Szlachta]

My son has a stock 74 duster with the 225 in it. We lost oil pressure on the highway a few days ago and assumed oil pump because the car had been sitting for a number of years before my son bought it and at 37 years of age and 137000 miles I thought it was good idea to change it anyway. When we drained the oild in prep for the pump change we noticed a very strong smell of gasoline from the oil so I said AHA! fuel pump leaked in to the block and thinned the oil. We changed fuel pump and put the nice new higher volume (supposedly 15% more) oil pump on. On the first start up the oil light when off after about 3 seconds (God I hate idiot lights) and idled smooth no untoward sounds from the motor or anything else. Now though there is a noticeable loss of power at all times and a very slight surging when driving at 65 mph. I don't know whats causing this now and would like all of your opinions as to what may be causing this and how to fix it.

Thank you

Szlachta

 

[67Dart273]

Well, it's possible that you damaged a bearing(s) or cylinder walls/ rings.

I've seen two engines in my lifetime suffer crankcase explosions due to a leaky fuel pump. If you ran that enough that you lost oil pressure, it probably had a LOT of fuel dilution

 

[Szlachta]

I hope we didn't do that. I could see a bearing causing this but I wouldn't expect some sort of failure or other indicator of this in a short period of time say like a 30 mile trip and if it was the rings or cylinder wall I would expect blue smoke from burning oil which there isn't, but then if I was more knowledgeable about this I wouldn't be asking questions here.

Oh yea. I checked the oil about a week and a half prior to this and it seemed a normal color and consistency. When we drained the pan it was black as coal and ran like water. I would assume there's no sludge left in that motor. It must have swelled the valve seals up some we don't even get a puff of blue smoke any more when we start it up after it's been sitting all night.




Szlachta

 

[dustoff440]

Oh yea. I checked the oil about a week and a half prior to this and it seemed a normal color and consistency. When we drained the pan it was black as coal and ran like water. I would assume there's no sludge left in that motor. It must have swelled the valve seals up some we don't even get a puff of blue smoke any more when we start it up after it's been sitting all night.


Szlachta

If you are running the Holley 1920 series it could be the "power valve", the metering block has an enrichment circuit that is supposed to work off idle and depends on two circuits that easily become clogged and not operating fully resulting in a bunch of gas being dumped in the intake and diluting the oil. Been there done that on a 72 Gold Duster /6

 

[green1]

Start with a compression check...

 

[Szlachta]

If you are running the Holley 1920 series it could be the "power valve", the metering block has an enrichment circuit that is supposed to work off idle and depends on two circuits that easily become clogged and not operating fully resulting in a bunch of gas being dumped in the intake and diluting the oil. Been there done that on a 72 Gold Duster /6

I had the carb rebuilt professionally about 6 months ago so I don't think that's the problem, I will check though, but when I changed the fuel pump I plugged the carb side and put air to the other and it leaked.

Start with a compression check...

Yep that's my next step this weekend, gotta find a tester that'll fit way back in that hole or make one.

Szlachta

 

[cudamark]

I hope we didn't do that. I could see a bearing causing this but I wouldn't expect some sort of failure or other indicator of this in a short period of time say like a 30 mile trip and if it was the rings or cylinder wall I would expect blue smoke from burning oil which there isn't, but then if I was more knowledgeable about this I wouldn't be asking questions here.

Oh yea. I checked the oil about a week and a half prior to this and it seemed a normal color and consistency. When we drained the pan it was black as coal and ran like water. I would assume there's no sludge left in that motor. It must have swelled the valve seals up some we don't even get a puff of blue smoke any more when we start it up after it's been sitting all night.




Szlachta

A '74 model should have a 1945 carb....completely different than a 1920. If you have oil dilution, it's probably the fuel pump. I'd be more concerned about bearing damage. Get a good "live line" test gauge and see what the hot idle pressure is. Low oil pressure is not likely to harm compression but it doesn't hurt to know what it is when you do a tuneup but there is no point in tuning something that is about to chuck a rod.

 

[powerwagonpaul]

I had the carb rebuilt professionally about 6 months ago so I don't think that's the problem

Szlachta

good rebuild shops are hard to find these days, most are only concerned with getting it to pass smog. i once paid a shop $140 to flip the carb/manifold gasket so it would pass smog. i figured out what he did three months later. learn to do it yourself and you are better off in the long run.
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