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76 Ford LTD issues (air pump?)

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Apr 5, 2015, 10:17 PM

Post #1 of 4 (991 views)
76 Ford LTD issues (air pump?) Sign In

I bought a 76 ford ltd last year, from an extended family member who owned it since new. It was fairly well taken care of...but it is an old car and has had more than a few issues.

I've had to replace all 4 ball joints, the alternator, the brakes, and I had to jury-rig a windshield wiper sprayer. So far I've been able to do it all myself, with some help from google, and my minimal mechanical skills. I do enjoy that about older cars - they're much easier to work on.

About three months ago, I had an intermittent problem start for the first time. It was very infrequent at first, and while it had increased in frequency recently, it still isn't an every day occurrence (and MIGHT be gone now - more on that in a bit). I am not sure how to accurately describe it - I would call it a 'surging' and/or loss of power.

Typically, it would just act as if I stopped giving it gas, and slow down a bit; anywhere from one or two up to ten miles per hour. It didn't matter if the pedal was barely pressed, floored, somewhere in between, or being pumped. After a moment, it would start picking up speed again - but usually it would happen several times in a row, and right at the same point of acceleration - like if I was at 40ish mph, it might drop to 38 or 35, then start picking up speed again; but right around 40mph, it would drop again.

Sometimes, it seemed the cause was while going up a steep hill, and accelerating. Sometimes it seemed like it was an overheating issue. Other times it seemed like it might be related to how recently I had filled up (or how low the gas was). It was just so random seeming as to when it happened, and at what speeds, that it was hard to figure out what the culprit was.

I won't go through all the things I tried to do to troubleshoot; at various times I thought transmission, fuel pump, carburetor, electrical, etc., etc., etc. I hadn't come close to figuring it out.

About three weeks ago, another problem popped up - a metallic clicking/ticking sound. It didn't seem to have any relation to the RPM of the engine, if I revved in neutral. It definitely wasn't related to the speed, as it sounded just as loud when parked as when driving. I thought it might have been the radiator fan slightly off balance, as I had that in an old nissan once, and it sounded very similar; but the fan wasn't wobbly but the sound seemed to be in that area; definitely not from the block (was worried about a rod or the lifters).

Okay, to switch gears - when I replaced the alternator, I noticed the drive belt and the alternator belt both were a bit worn so I bought some replacement belts and switched them out. As far as I could tell, those were the only two belts in the engine (the AC belt wasn't there, as some time in the past the AC had been completely disconnected, though the compressor is still in there - I have no idea if it would work or not).

But the day before yesterday, as I started the car up again in the middle of a longer trip (had been driving in the heat for about 90 minutes, stopped for 10 minutes or so, and was starting it back up), I heard a distinct belt squeal. Not a brief squeal, but a constant squeal. for about a minute. Then I smelled burning rubber. I parked the car right away, and as I went around to the hood, noticed two ends of a smaller belt hanging from below the engine. I barely touched it and the belt fell into my hand. So I am not certain exactly where it came from.

Based on where it was, and looking at the various parts of the engine that might hold a belt down there, and using a bit of google searching on the part number listed on the belt, I *think* it is an "air pump" belt. Now, I am no mechanic. I have worked on cars a bit in the past, and am not incompetent, but I haven't spent a ton of time under the hood. And I have never heard of an air pump before. Now, from google, I think I have figured out basically what it does (did) - something to do with emissions, in short.

Since that belt broke, I've driven the car a few miles, and that metallic clicking/ticking is definitely gone. I haven't had the power surge either since it broke, but that isn't a definite sign of anything, sine it was getting more frequent but still very random and intermittent. It might pop up again. But I have a suspicion, based on what I've read on air pumps, that it won't come back.

But I am no mechanic, as I have said a few times. Unfortunately, I can't afford to take the car to a real mechanic to be sure that my internet searches and minimal mechanical knowledge might be right.

Does anyone here know if that surging problem could have been caused by an air pump that was on its last leg? Or if not, might you have any ideas what else could have been causing it?

And the ticking sound; I assume it was a fan in the air pump that was going out, or some other component of the air pump...?

And finally - as far as I can tell, it will probably do more good to leave the air pump disconnected, I read that the air pumps of the 60s and 70s often caused excess heat and could damage exhaust valves... and since as a 'classic' car, I don't have to get emissions testing, I think the only negative would be a bit worse gas mileage. But again, I'd like to be sure.

So, yeah - sorry for the super long tale. I'm always a bit longwinded. But if you could offer me any advice, I would greatly appreciate it!

Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 6, 2015, 3:51 AM

Post #2 of 4 (971 views)
Re: 76 Ford LTD issues (air pump?) Sign In

Of all that you can't say which engine is in it!

OK - Most would be listed on an orange tag on driver's side valve cover or can tell by 8th digit of vin. Almost all were 351M/400 essentially the same.
If "air pump" and any parts are hacked up on it look for them used and install it as intended. I don't need to check it's available rebuilt and you'll lose the deposit for a core or get a used one. If it turns from small (sharpish) fins it's fine 90% of the time.

Parts: The big box stores have on line shopping but for used parts may have some troubles. That's where it will totally help to know which engine.

A/C - If the only think on that belt forget it for now till you have it all running properly and should be able to.
I'm not googling out what this is like have owned many never mind how many worked on - tons. This should have a 2 barrel carb that's quite simple for the problems of it driving that's most likely alone with every dang vacuum anything in it. If old, one by one can do them all.

These like anything didn't care for oil change neglect and your noise will probably go away if you just change oil many times in a row with just a few hundred - 500 or so miles if you can do that with it running ok that will or should stop common valve ticking.

Switch to synthetic when it quits or find out what if it doesn't.

Find out which engine please. Only super rare optional one would be the 460. Lame for the size of it and a wild pig on gas - the others were jus plain pigs. Strong chassis cars - worst problems would be rust in front or rear wheels frame was common to rust out, back bumper supports which is a steel support behind chrome would fail and bumper fall right off but looked fine the day before - know these cars way too well.

Last same common engine would be the 70 Continental Town Car with a 400M or all monster Lincolns sold to CA in 78 and 79 where if parts are a problem you'll find them for those as nobody cars much about a monster plain LTD.

The other problem if you haven't found out yet as they are the last of the longest passenger cars made. Hard to park if nothing else. Most other common issues short of rust outs were pretty straight forward. Check that rust as mentioned. If that bad and not going to go nuts (I wouldn't) don't keep it hate to say. It marks the end of when frame goes where they do,


Ultimate Carjunky / Moderator
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Apr 6, 2015, 4:53 AM

Post #3 of 4 (966 views)
Re: 76 Ford LTD issues (air pump?) Sign In

I read that the air pumps of the 60s and 70s often caused excess heat and could damage exhaust valves

They still use them today and I haven't seen one damage exhaust valves.

You should inspect the diverter and check valves if you plan on replacing the air pump. If a check valve goes bad, hot exhaust gasses will burn up your new pump.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 6, 2015, 4:55 AM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 6, 2015, 5:36 AM

Post #4 of 4 (961 views)
Re: 76 Ford LTD issues (air pump?) Sign In

Back to this: OP - call it "smog pump" for easier looking around for set up. Wild high chances this would come with an "H" code for either big block 351s (one was an "M") same VIN designation for engine. Two pumps possible one with hose on body one out back and you need to know.

Up top you mentioned both it didn't drive right at certain speeds and throttle then the noise to be determined. These years that smog pump (I think most) you could just do without it totally and didn't change the way the engine ran. Idea is add air when told to exhaust (stuff still does that) to burn up any unburned extra fuel (hydrocarbons) while it is hot and fast before going on to converter. If it ran like a top all the time (it's not) it wouldn't matter too much. It can save the converter(s) if a CA car say so please.

The #1 reason for not running well or the way you mentioned will be the carb. Hope nobody changed it to what would be a mess now like manual choke or another type as OE was fine and so easy almost idiodic. Kit if all there would be periodically needed and suggested anyway now as the methanol in fuels would harm OE gaskets and wouldn't be so great anyway. Fuel pump diaphragm can be changed without removing the carb at all.
Shown lower right in this pic.........

Wildly common. ? Whole carb showed the choke used a tube to exhaust and all failed in a few years so choke would stay on too long as in WAY too long.

Easy fix with a kit really even this old. If things are all butchered up that will be the endless problem. Converter is probably missing or bored out by now and has been for ages. It doesn't do squat for how it runs but can plug up and many did when most vehicles on the road used leaded fuel both higher octane and less expensive cheated and wrecked converters in no time. Not just the owner of the cars the gas stations could get leaded fuel put in the unleaded tanks or didn't know and that's what was delivered.

Tough time for that period about leaded/no lead fuels and the newer ones almost all had converter just beginning in model year 1975 - none earlier.

Back again. If frame is rusted in front of back wheels it can be welded up but at the age for actually not a very special car I wouldn't bother with it at all anymore unless some sentimental value to you,


If all that stuff is now missing

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