Moss Motors, Ltd

Hello,

I am still very new to the forum and have not had my Sprite very long.  Yesterday, I had it out on the road after getting it back from my mechanic.  It was a round trip of about 100 miles.  The car ran pretty well but I noticed a few things.  The oil pressure at initial start up was between 40 and 60 pounds.  However, as I drove along, I noticed the pressure slowly going down to around 20 pounds at cruising and really low at idle.  There was no noise or smoke and it seemed to idle smoothly but that worries me.  I have a 1968 Thunderbird that had low pressure and it turned out I need to replace some bearings.  Might that be a problem with the Sprite?  The person I bought it from did not have a history on the engine, but he owned the car for about 5 years with know problems.  This morning I went to start the car and pulled out the chke a little like I did.  The car started but ran really rough and would cut out all together.  Also, the choke will not go all the way in now when released.   At least it is in my garage and I am not out on the side of the road.  I don't know what to do at this point.  i'll try and start it later but why when I realease the choke, it won't go all the way in now?

 Sorry for the long message but I wanted to make sure I cover everything so that when I go back to my mechanic, I can talk somewhat intellighently about what is going on.  thank you all for the helpful advice you have provided to me in the past,

 

thanks,

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Marty
1968 Sprite MK IV 1275cc

mxandre,

The oil pressure for your Sprite will drop at slower idles. 40-60 pounds of pressure at start-up is great news! As the oil heats-up, the pressure tends to drop, as long as you have about 40 pounds or so while on the highway, you should be OK. 20 pounds at idle is to be expected.

A few other things here...These pressure gauges are not the most accurate things. A cheap replacement gauge (about $15) from an auto parts store can confirm or belay your fears. There's no need to mount it, just hook it up temporarily and go for a ride. The tube secures to the engine via a 7/16th brass nut, about 7 inches below spark plug #4. 

Also, what type of oil are you running right now? 20W-50 is recommended for most driving, but 10W-40 is good for the colder temps of winter.As long as we're on the topic...don't forget the ZDDP!

On to the choke...The cable may be kinked, in need of some graphite lube, or for the price, just replaced. Take a look at where the cable connects to your carbs, it's the cable directly behind your rear air cleaner housing. You can use your finger to push down the lever to which it connects. Make sure of course, that your choke cable is unlocked before you do this! Twist the knob counter-clockwise about 90 degrees to unlock the cable. 

As far as the car running rough, since it ran well for the 100 mile trip, it's probably something very minor, and an incorrectly adjusted choke will produce this symptom. You can do a touch of troubleshooting by simply inspecting the spark plugs. Any plug that is wet with either fuel or oil, OR is black with carbon indicates a problem with that cylinder. There's lots of ways to go from here and most of them are quick and easy fixes.

My money is on the choke adjustment/cable though.

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On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"

'68 Sprite 1275
'76 Midget 1500

20 pounds at cruise is an indication that you have pretty badly worn bearings and or a worn out oil pump. Just how "really low" is the pressure showing at idle?

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Hello All,

Thank you all for your replies and help.  The pressure at idle is around 10 pounds after the car has warmed up and I am sitting at a light.  I spoke with my mechanic today and he said the same thing that it might be worn bearings or a bad oil pump or both.  So she goes to the shop this Friday to have the oil pan dropped and see what is going on. I am wondering if I should just have it flatbedded to the shop as I don't want to do any damage to the rest of the engine driving it there.  It is about 40 miles to my mechanic.

 I did however get the car started today after working with the SUs.  The idle is a bit loopy but she  drives smoothly with no hesitation or lag.  No smoke or noise either.  I think once the oil pressure issue is diagnosed and sorted out, it should run beautifully  I have a feeling the bearings are going to need replacing. 

 Thank you for any and all advise.  This is a great forum:-)

Marty

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Marty
1968 Sprite MK IV 1275cc

I wouldn't worry about the 40 mile drive. If it is worn bearings, 40 more miles didn't hurt much more!

As for the rough running, I'm sorry to tell you, but fixing low oil pressure will not improve that. On the other hand, from what I've read, it sounds like the carbs and/or choke are just in need of adjustment.

It is possible that you could have scared the cylinders thanks to the low pressure, but I seriously doubt that since your pressure is not too-too bad.

Keep a good thought, be positive, and once you get her back from the doctor, we'll get her running smoothly! While she's there at the mechanic though, take the time to go buy a manual for this car. It will be the best money that you could spend on her! I have the Haynes book #66015, but there are several others that are fine too. Moss offers the Heritage books on CD-ROM, I have one for my 76 Midget, and they are worth the price.

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On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"

'68 Sprite 1275
'76 Midget 1500

Marty-

Have your mechanic do a pressure check or do one yourself before going through the trouble and expense of replacing the bearings. If the compression is good, go for it, but if the compression is weak/low it would probably be more economical in the long run to address all the problems at once.

Best of luck and let us know what happens.

 

LCJUTILA 

LC is right...(sorry, I meant to mention that)

For reference, the compression should be within about 10% for each cylinder.

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On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"

'68 Sprite 1275
'76 Midget 1500

Hello,

 

Thanks again for the great advice.  Already bought the Haynes Manual.  The previous owner also provided a manual on the SU carbs.  Getting the carbs adjusted should straighten out the idle hopefully. Been doing a lot of reading and absorbing information.  I will also have the pressure test done as advise.  Might as well get it all taken care of at one time if there is an issue with compression.  She goes in on Friday so I should know what is going on and what has to happen some time next week.  I have a trusted mechanic who has owned 5 of these cars including a Bugeye.  I'll be putting in some sweat equity at the shop so I'll be learning as I go along.   I'll keep you all posted on her progress.  Thanks again.

 Marty

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Marty
1968 Sprite MK IV 1275cc

Hello,

Just got the  68 Sprite back from my mechanic.  all is well.  The oil pressue issue turned out to be a bad sending unit and gauge.  It also needed a new choke cable as the one on it was frayed??  A set of new air filters completed the repairs and now it runs nicely.  Those were relatively simple fixes I am happy to say. 

Now, I am still hunting for literature.  I have the Haynes Repair Manual  and the Porter Service Manual which are very helpful and provide a lot of mechanical and routine service information.  What I would really like to locate is a Sprite MK IV Drivers Handbook, the one that comes with the car brand new.  Neither Moss nor Victoria British have originals or reprints for the MK IV series.   I have found a lot of the MK1 handbooks on Ebay both USA and UK.  I have even found a MK III handbook, but I cannot locate an MK IV Handbook.   If any one has any suggestions on where else to look, I would greatly appreciate it.  Thanks again for everyone's help and support.

Cheers,

Marty

 

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Marty
1968 Sprite MK IV 1275cc

I may be wrong, but I think I nailed all your problems in my first post!

Good for you, I'm glad there wasn't anything too extensive.

As far as your handbook request, I bought the Heritage CD for my 76 Midget through Moss. Included on that CD is a PDF of the original owner's manual. Perhaps you can find one for the Sprite.

Good luck!

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On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"

'68 Sprite 1275
'76 Midget 1500

Sorry, but I'm in the "crossed fingers" camp with this repair. You say that BOTH the sender and the gauge were bad?? Something sounds strange, though I'm not trying to impune your mechaninc. Keep watching that OP ga. Was the oil changed during the repair? Was it replaced with the same grade as was in it? HMM...

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Hello,

 Thank you for the response and concern.  My mechanic indeed replaced the op gauge and the sender  We discussed the bearings as I told him I had a similar problem with my classic Ford and it turned out to be the bearings.My mechanic didn't think we needed to go that route just yet and we would continue to monitor the oil pressure over time to see what it does.  After his repair, the pressure at start is between the 60 and 80 mark and as the car warms up it starts to come down and settles just below the 20 mark when the car is completely warmed.  I was out driving the other day and the pressure on the move stayed just below the 40 mark and would drop to just below 20 when I was stopped and idling..  Again, there is no smoke or strange noises at this time.  The oil was changed and 20w50 was used as before. 

Any suggestions are welcomed as you all have much more knowledge than I have as I am still in my learning curve and I suspect will be for a while:-)   The car does seem to run nicely now. We'll see where this goes and I'll certainly keep you posted.  Thanks again.

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Marty
1968 Sprite MK IV 1275cc

Marty,

It sounds good. Just as your mechanic says, keep an eye on it. My advice would be to change oil a bit more frequently as well, and look at the oil you take out. Enjoy your car, mate.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon