1970s 1979 425 engine, won't stay running.

[Michael Petti]

I could not see that it was crimped. Sorry, probably not rebuildable.

[NickD]

Hi all. Well, I now have fuel to both sides of the new fuel pump, but as some of you have said the carburetor will have to be rebuilt and that is where I am at this point. The carburetor is off the car and on the work bench.
I talked briefly about fuel pumps in my post above. Let me tell you the fuel pump story. It is my opinion that the Airtex 41204 pump is not the right pump for this engine. I was not comfortable with the Airtex pump, so I did not try to install it. The configuration of the pump arm was different from the original pump and the diameter of the pump body was also different everything else was identical to both pumps (see pictures for pump comparisons. Please disregard the measurements on the ruler as they mean nothing to the comparison). With that said I bought a Carter M6952 fuel pump. Both pumps (Airtex and Carter) had part identification numbers on them. The Carter was clear and easy to find. The Airtex was hidden and hardly visible without magnification. I Carter M6952 pump, which other than the metal plate riveted to the pump arm is identical to my original pump. I called Carter technical services, and the gentleman told me that they eliminated the metal plate because they went to a hardened steel arm. Well, that's my pump story. I will post an update once I rebuild and install the carburetor and the vehicle starts, I hope.

[TJ Hopland]

Which one is which color wise?

Amazing that when you got a different brand you actually got a different pump.  A few years ago I was thinking I had an issue with the previous gen cad one and I bought 3 different brands and they were all the identical pumps.   I no longer recall the brands but if I had to guess I would say Delphi, Carter, and Airtex. 

[NickD]

The blue one is the original pump in all the photos. Something I forgot to mention in my last post is as follows. On the Airtex pump the pump lever was staked in place in the pump housing by some type of crimping method. Whereas on the Carter pump the pump lever was set in place with a roll pin, just like the factory pump.

[TJ Hopland]

Of the new ones which is which?   Gold vs silver?

[NickD]

carter is the silver one. gold is the airtex pump.

[NickD]

UPDATE_2

Hi All
Well, the fuel system problem is under control. With the new tank, sender, fuel pump and carburetor rebuild. The old dog is up and running.

However, I still do not have oil pressure. I removed all the spark plugs and cranked the engine for a while (as someone suggested in this post) and still the light did not go out. I installed an oil pressure gauge and started the engine and still no pressure. I did not want to run the engine long, so I shut it down after about 45 seconds. I replaced the oil pump with a known good used unit I had. I followed the instructions in the factory manual. Still no oil pressure! When the engine is running there is a slight lower end thumping, and the engine does shake. To me it does not sound like main bearing knocking as it is not a loud knocking sound. When I accelerate, the thumping does not appear to get any louder. There is also some lifter noise, but not a lot. I am kind of at the end of the line unless you guys have any more advice or ideas as to what I should try next.

[TJ Hopland]

What happens if you crank it without the oil filter installed?   The filter is after the pump so this will tel you if its able to draw oil out of the pan.   It should come out the outer area of the filter mount.   The inner leads to the engine.

If you don't get any oil there there has to be an issue with the pickup like its completely clogged or is loose.   IF you got oil there there then its got to be something like a galley plug has fallen out and is bleeding off all the pressure.

I would have been working at this before doing the rest.  If you aint got any oil pressure it doesn't take any time at all to trash the engine assuming it wasn't trashed before you got it.   

[NickD]

TJ, I removed the filter and cranked the engine as you suggested. I am getting oil. The vehicle had been sitting in a garage since 2006. I guess it was parked due to the oil light issue.

[TJ Hopland]

So that tells us the pickup tube is mostly attached and not completely plugged.  Are the pumps you have been using aluminum? Or iron?   I believe the originals were all aluminum and replacements are iron.   For many years Melling was the only one making them and they had a known machining tolerance issue in the regulator that would allow the piston to jam up in the bore which leaves you with virtually no oil pressure.

What do you get if you remove the oil pressure sensor/gauge and crank it?  Do you get oil out that port?  I'm just wondering if its getting lost before it gets that far or if its pumping OK but there is just a ton of wear and it can't build pressure.   It would be rare for one of these engines to be that beat up. 

If it was a clogged pickup screen I would think you could initially build some pressure but not maintain it as it sucks more crap up and packs it tighter in the pickup but that doesn't seem to be happening here.       

[V63]

This does not seem to be progressing in an encouraging direction. Your next avenue might be to pull the oil pan.

[TJ Hopland]

Ya, being a Deville it should be possible to pull the pan without removing major components.   See how much crap is in it and wiggle around the bottom end.  If its not building any pressure I would expect to find things like rod caps to wiggle just by grabbing them.

[NickD]

Both pumps are aluminum. The pump that was originally on the engine was painted blue, so I am assuming it is the original pump. The other pump is all silver color, so I am guessing that was a replacement pump at some time before I got it. I know that pump is good because it came off of a running engine. I also checked it for wear, and it was within specification.

I packed the pump with petroleum jelly as the factory manual suggested, is it possible that I did not allow the jelly to get sucked thru the system before shutting the engine down. I did not want to run the engine long as I am trying to minimize the damage. I only ran the engine for about 45 seconds.

With the gauge/sender removed I get on oil coming out of the port.

Someone in the post suggested checking for a plugged exhaust system. I would think that a plugged exhaust system would have nothing to do with not getting oil pressure. What do you guys think?

[TJ Hopland]

Plugged exhaust would not effect oil pressure at least short term.   Long term maybe it would raise temps which would lower oil pressure but that isn't the biggest problem here.

Next I would say pull the valve covers and check to see that all 16 rockers are working.  The only easy(ish) thing I can think of is at one point a valve was stuck which bent a pushrod which then let a lifter pop out of its bore and that is where all the oil pressure is bleeding off from. 

If the lifter is still in the bore a new pushrod may get you back working again.  If its completely fallen out you will likely have to remove the intake to get it back in there.

[V63]

I made the suggestion of plugged catalytic converter as related to 'not starting or running'. But that would not have not related to oil pressure. Unfortunately your scenario is not encouraging. Could be spun or damaged bearing, probably need to pull the pan at this point.

I have a good 1977 425 assembly with under 80k miles in my shop. 85004.

[NickD]

V63. Thanks for the engine offer, but if I decide to do some further checking and it turns out to be bad, I am just going to break the old dog up and sell her for parts. I must say that I did have some fun getting to this point, as it has been quite a few years since I opened the toolbox and got my hands dirty.

[V63]

Maybe post some pictures of the patient, we can provide some moral support

[NickD]

V63- here are some pics.

["Cadillac Kid" Greg Surfas 15364]

Nick
If you didn't pack the new pump with Vaseline it has lost its prime and doesn't have the suction to draw oil up and into it
Greg surfas

[V63]

I believe somewhere in the thread he verified oil was flowing but not building pressure.

I simply changed my oil in a 472 once and instantly I had no oil pressure and yes I had to pull the pump and pack it with petroleum jelly. That indeed worked. My policy now is I change the oil first THEN the filter last after filling the new filter with oil first