Unpredictable B-310

[datx]

Hey guys I'm new to the site and hoping someone can give me some advise on a B-310 issue I am having. First off a little description of my datsun. I finally was able to buy the first car I ever drove a 1979 datsun B-310. This was my Grandpa's car and I only drove it for a short time when I was 12 or so years old when we went to go feed cattle. He had bought the car from the orignal owner years before this and had repaired it following a wreck it had been involved in. He parked the car years ago (I estimate it set in a field for 15+ years) before my uncle who had inherited it final sold it to me after trying for years to purchase it from him. It had been parked due to a faulty slave cylinder (that's all). Once obtained I started tearing into it thinking it would not be to big a project to get running again - this is were I was wrong. You see this car only has 27,700 original miles on it and the car was under coated etc and amazing really has no rust issues (just a couple small holes in the passenger floor that will need small patches). So far here is what I have done to the car; drain old gas and flush gas tank with fresh gas, remove and clean carb, purchase new mech fuel pump, replace fuel hoses, replace slave cylinder, replace all original fluids - diff, trans, oil. Following this I have driven it some and it has 2 modes - 1. runs perfect idling etc 2. Barely runs at all, blue smoke comes out the exaust,etc. I cannot figure this issue out. The first time it happened I was warming up the engine to drain the old oil and all of a sudden after running fine for a while it went from running great to smoking and barely running when I kept the pedal down. I changed the original oil out noticed one of the spark plugs was loose and that seemed to fix the issue until tonight it will not even start without a lot of pedal and smokes like crazy (blue smoke) when I am able to keep it running - basically it will not even run now. Keep in mind I have had this car running quite a bit since the first incident and it did run fine. Is this some sort of timing issue? I am not sure where to look??

[Cuts metal like mad]

auto or 5spd?

[ppeters914]

And, as Click 'n' Clack the Tappet Brothers say, what color? :lol:

[datzenmike]

Easy stuff first:

 

How much oil did you put in when you changed it? Not what the dip stick reads, but how much you put in.

 

 

Pull all four plugs and keep in order. How do they look? Are they equally oily and covered with soot? Are two adjacent plugs dirty?

 

If you can, borrow a compression tester and test and record the compression for each cylinder.

 

With luck the valve seals (one or all) are bad or maybe a head gasket. This is reasonably cheap to fix and no ill effects. With a lot of luck, it is just overfilled with oil.:mellow:

 

I can't see the oil rings being worn on so low a mileage car. Think of them as a wind shield wiper, wiping the excess oil off the cylinder walls. I suppose one or more could be seized from sitting so long and unable to remove the oil properly and leaving streaks.

 

Wait and see what the plugs look like and what compression you get.

 

mike

 

auto or 5spd?

 

(hint) slave cylinder :D:D

[Cuts metal like mad]

hmph... passed right over that... reason I asked is that this sounds similiar to another guy who did a motor and trans swap on here, can't remember who, but turned out to be a valve or some such part that went between the tranny and engine.

[datzenmike]

Yup. Thought that too. Our Ford van kept loosing auto tranny fluid and strangely the motor oil level was rising???

 

Sent it to the dealer who swore up and down that couldn't happen with that year. There was some kind of vacuum switch on the tranny that was leaking and fluid was sucked up. But how it got past the intake and into the bottom of the motor I just don't know. Didn't smoke either.

Turned out the tranny may have been swapped for an older model before we got it???

[ggzilla]

Datsun A-series engine take ONLY 3-1/2 quarts. Believe it or not. I only put three in, it comes to the halfway point on the OK part of the dipstick. If you put in five, drain 1 1/2 quarts now and that should clear up the smoke.

 

Yes, what color is this B310?

 

I recommend a compression test. It may have a (slightly) blown head gasket. I cannot think of another reason why blue smoke would come and go like that. What you are looking for is not a specifc psi number, but that all four cylinders are the same compression (within 10% of each other). If two are low, and two are high, that is an indication of a blown head gasket. Not proof, but an indication.

[datx]

Thanks for some of the helpful suggestions. The datsun is yellow, it is a sedan with the A14 motor paired up to the 4 speed manual tranny. I have all the original owner documentation along with owners manual which specifies fluid capacities. When changing the oil I put in the 3-3/8 qt that the manual calls for with oil filter changeout. I checked the dipstick tonight and it is a LITTLE over the full mark but not by much - maybe its possible that I did not get all the old oil out since as listed earlier it started acting up for the first time when I was trying to warm up the oil for the changeout. I will try draining some oil out this weekend to see if this helps any. I checked the spark plugs and all looks well. Today I purchased a compression tester so I will check the compression this weekend and post the results to see it this is normal. I really would like getting this car back on the rode soon my son has just joined a travelling baseball team and we plan to have a lot of fun in this car traveling to games. thanks

[ppeters914]

Does it look like this yellow one?

 

[datx]

Yes it looks like the yellow one. I did drain some of the oil this weekend (about 3/4 a quart) and it did stop smoking. The dipstick is reaching about 25% up from low mark referencing the gap from L to H. For my other vehicles I would call this low but if it works for this one so be it. I checked cylinder compression tonight and below are the results;

cylinder 1 = 175 psi

cylinder 2 = 175 psi

cylinder 3 = 180 psi

cylinder 4 = 180 psi

Do these numbers seem correct? I have never checked compression before so let me make sure I did it right 1. warmed up engine 2. disconnected center distributor wire 3. removed all spark plugs 4. I did not tie open throttle plates because I did not want to remove the air box so I just put the accelerator to the floor 4. turned it over about 4 times 5. repeated for each cylinder. Was holding the accelerator to the floor sufficient? My wife helped me and messed up a could times and forgot to hold the accelerator down on a couple of the cylinders and they each read 150 psi when this happened. Lastly I did replace the spark plugs tonight and it does start better but not without gas so am I back to a carb issue? I removed and fully cleaned the carb when I first got the 310 and it was idling great now it will not stay running without some pedal to keep the rpm's up and idles rough before quiting when the pedal is released. One last observation I will note maybe this will give a clue to my current issue. Before this issue began when it was idling well (not smoking etc) I did notice that it would up and quit after running a while. I discovered that there was vacuum building in the gas tank as it ran and once it set for a while or I opened the gas tank to equilize the tank it would fire right and and start running again idling great. How that it idles rough I no longer have vacuum after running it for a while in the gas tank actually I have a little positive pressure in the tank?? Thanks in advance for any additional suggestions.

[bonvo]

sounds like it could be a vacum leak? make sure all the vacum lines are connected to the cab mine wont run unless they are

[ggzilla]

Yes, those are good numbers for compression. They are all close, that's what's important. Holding throttle open has never made a difference with any stock engine I've tried, I now just leave throttle closed.

 

You should do both wet and dry compression test. You did dry. Next, squirt motor oil in each cylinder then check again. If the numbers go up it indicates bad rings.

 

 

The tank should have no pressure in it when engine is running. The tank is vented through the vent line, one of the three steel lines that come from tank up to the engine compartment:

1. Fuel supply line

2. Fuel return line (to keep fuel cool by recirculation, this is not for pressure regulation)

3. Fuel tank vent line

 

The vent line should go to the charcoal canister, however there is also a check valve in the line, probably back by the tank.

[hogboy52]

..

This may not apply in your case but I went through almost the exact same conditions with a '77 620 which the PO could not get to run and had been sitting for three years. Leakdown test near perfect, cam and ignition timing right on, would idle OK but puke with throttle: plugs black and oily. After many hours of dead-heading, I replaced an already new condencer and it has ran fine since.

What clued me on was I took the timing light and pointed it at my face while advancing the throttle and I could see all the blank spaces that occured at higher RPM's.

[datx]

Well looks like it was the carb. I inspected all the vacuum lines and found nothing so pulled the carb again, cleaning it again. I did notice that even though I did have the carb tightened down that I may have been getting some leakage between the valve body assy and the plate. Once recleaned a reinstalled the carb using gasket sealer on the gaskets and that did the trick. Car is idling good now. Also car has not smoked since I drained some oil down from the full mark, thanks for all the suggestions it helped me learn a little more about my datsun.

[BluEvo210]

Well looks like it was the carb. I inspected all the vacuum lines and found nothing so pulled the carb again...

 

I wonder if I'm having a similar problem with my B310. The one that runs only runs in "Mode #2". I'm leaning toward thinking it's a carburetor problem, because when I pulled the spark plugs, the #1 & #4 plugs looked OK and the #2 and #3 plugs were wet with raw gasoline.

 

I'm glad I read this thread and will be on the lookout for others like it. I have a year to read about Datsun diagnosis before I get back home to my cars and can do something about it.

[LenRobertson]

I'm wondering if the smoke issue could have been an intermittent carb problem. Unlikely, I know, but sticky choke or sticky float needle valve could cause it to run super rich. I know we will get into a blue smoke/black smoke discussion now, but how certain are you of the color?

 

I'm very concerned about running too little oil in the engine, thinking it is necessary to solve the smoke problem, if it may have been a goofy carb. If you run it much below the Full level, there is less room for error if it uses any oil and you forget to check it. Unless you have reason to think the wrong dipstick is in the car, I would get the oil level up to the full mark. Until you drive it awhile, it is hard to know if it might use a certain amount of oil.

 

It is great the compression is so good. It sounds like you have a great little car.

 

Len

[ggzilla]

If the oil level is between the L and the H marks, it is not too low. It is in the normal, acceptable range. Further, (unlike the L-series engines) you can run the A-series so low that with no oil showing on the stick, it doesn't damage the engine. They have a very good sump on them (at least the B110 & B310. The b210 and FWD cars may differ).

[LenRobertson]

If the oil level is between the L and the H marks, it is not too low. It is in the normal, acceptable range. Further, (unlike the L-series engines) you can run the A-series so low that with no oil showing on the stick, it doesn't damage the engine. They have a very good sump on them (at least the B110 & B310. The b210 and FWD cars may differ).

 

That's good to know. I grew up with engines holding 5 quarts or more, usually oil burners, so I get paranoid with engines holding about as much oil as a wok doing stir fry. My wife's Cheby Prism (or is it Prizm? Whichever, GM musta been really desperate for model names) holds about 3 1/2 quarts, and uses oil. Just drives me crazy. I know it won't be a cheap engine to fix if it runs out of oil.

 

Len

[ggzilla]

Oh, it'll be cheap to fix. Chevrolet bought the Prizm engines from Japan. If it's good enough for the General, it's good for America.

[moparvwfreak]

yup. the Prizm is just a rebadged (at least the older ones) Toyota Corolla. those are one of the few Geo\Chevy cars i will own, short of my caprices anyway.