Doug and Jose,
Many thanks for your kind assistance and advice. I drove the Jag for about an hour this morning on a full AGM battery, and the voltmeter on the dash started at 10, up to 13 for a minute and then down to 11 where it stayed. Probably that a rectifier diode is breaking down under load or heat. Drove to an AutoZone where they 'checked' the Alternator. I thought they might do more, but they just put their charging system device on the battery terminals while the engine was off and then running so I think that all they did was verify the alternator was not generating adequate and regulated voltage.
Soon as I reclaim my garage I'll pull the Jag in and begin disassembly! I'll verify voltage/continuity again along the process. We moved and downsized early this year and I gave away all of the stuff that I really wish that I had right now!!! And still have stuff in the garage that needs to be shelved or given away. It seems that nobody here in this neighborhood is a wrench. (too upscale??) Certainly I'm not a wrench but I have had my fun trying. I just finished replacing a $535 tube motor in a 16' x 11' roller sunshade which was a fun distraction.
I am slow with this and will follow your advice. Fortunately I brought two jackstands and a full set of 1/4" sockets, and a forehead light, etc. What I also have is competition for my time -- it is absolutely beautiful these days in SW Florida, but daylight is short.
There is a YouTube video of 'Jessie' replacing the alternator by removing the radiator. Looks like more trouble than the bottom method but he had been there before when he installed radiator electric cooling fans.
Many thanks to you my friends!

 

I am familiar with the youtube Jessie. I do not care for his approaches. Removing the radiator is absurd.
that is like drilling a tunnel through a mountain to get to the other side when you could have walked around the mountain to the other side.

 

1. Is your charger Smart? Old tech chargers and AGM batteries do not 'get along". I got a Schumacher a few year ago to replace an older Schumacher.. Their tech was very informative.

2 Do not rely on the fascia voltmeter for accuracy, it is not a guage, only an indicator. HF sells nice units very cheap. Not Fluke quality, but fine for a DIY guy., I have three. Analog, digital and inductive..

3. Get down and under. right side where the transmission and engine conjoin. There is a braided ground strap. Clean it at both ends. protect with grease or oil.

4. I prefer ramps to jack stands. . More stable. Chock the wheels!!!!! Park alone is not enough And for durn sure do not rely on the hand brake alone!!!!!!!

5. For added conficence., shop for and buy a load stester. Carbon pile or electronic.. it tells the real condition of a battery, not merely it's stateof charge...

Weather around here is really nice. Shoulders putting up a fuss though

 

Thanks JagCad, I am listening and here is reply to your help:
1. Charger is probably smart. Purchased 3 months ago and has an "AGM" selector switch on the front. Using Digital Volt Meter (DVM) I note proper charging.
2. I had an old Beckman and Simpson, now just a simple and new DVM that works fine.
3. Braided wire ground at engine to body looks like new. Will clean and retorque tomorrow.
4. I have 5K lb stands, keep 2 jacks in place, and 'build' backup blocks as 3rd. Had a friend's son killed in his driveway when car dropped on him. Very sad.
5. Had load tested at AutoZone and watched him. Battery is 70% on listed 800A CCA and holds charge. Don't know age, is Optima Red Top of unknown age.

 

Following your advice. Here is my update:
Took the alternator out as you described. Found evidence of replacement of original alternator including three threads from tight on one of the alternator mounting bolts and fasteners missing in other locations, and it is a Bosch model alternator. Although I am perhaps capable of testing and repairing the alternator with your help, I'm going to take the alternator and battery to an Alternator shop tomorrow and at least get tested. Mounting and replacing it looks like it will be fun too! Thanks for your encouragement and fun.
I have trans fluid leaking to floor, appears that it is from the pan gasket. I chris-cross tightened the fasteners without strong-arming them and got about 1/8 to 1/4 turn. Would it be worth draining and replacing the gasket while it is up or am I unlikely to stop the leakage?
Many thanks again!

 

the Bosch alternator is usually used in the 12 cylinder cars, Doug knows the part number.
The Lucas alternator was used in the 6 cylinder cars.
Both are reliable but after 30 years, they all start to fail eventually.

​​​​​​as to the leaking, you need to find out where the leak is. Raise the car level on a lift with engine running. Check with a bright lamp.

 

Update on my alternator and charging problems. Received the alternator back from shop. Axial shaft thrust was more than 1/16 inch but alternator ran well with diode trace consistent and showed proper rectifier function. Repairman said that when he reset the alternator shaft bearings that he found the brushes on the slip rings not riding properly so he centered the brushes. Despite those problems, the alternator looked perfect before repair on the test stand. I reinstalled the alternator, but have not restored the parts around the alternator pending information from you.

As a safety insurance that the charging system works, what do you think about installing a direct ground from the alternator casing to the car body or to the body post for the battery? I'm taking the alternator out to rigorously clean and polish the alternator mounting/bolting area. Also, as it is difficult to monitor the actual exciter volts to the alternator I am considering an extra connection to the field exitation terminal.

The alternator belt could be slipping, but it was tight and seems very new and not smooth.

These may be overkill?

 

Phil, I was planning on installing a ground strap from alternator to body. Don't know if it will make any difference. I am worried it might create a Ground Loop, which is something that happens with music equipment and translates into a HUM through the speakers when too many grounds are connected.

 

No problem with adding an extra ground at the alternator. I've done so as have others.

As for the extra wire at the exciter terminal....I do't see a problem there either

Cheers
DD

 

Son added a ground from the wing wall to the engine block on my lump. fixed an odd problem!!!!

Aye, some trepidation on "floating ground". None audio or otherwise, so far.

Phil:

I made a patch cord for my HF sourced VOM. Plugs the leads into the cigar outlet.

I can read voltage at various loads and rpm's

Load test of rated 800 CCA's at 70 %. Not all that good, Marginal in my view.

 

Removed the alternator today, cleaned up the mounting bracket, removed some paint and sanded smoother. Put enough back together to test the alternator with the running engine. All sat!! I think that the real culprit was the slip ring brushes bouncing due to the axial thrust on the shaft that the repairman fixed. Likely this rebuilt alternator was installed at least 3 years and 1500 miles ago. The other work and grounding straps were insurance.

Next is the oil leak from the transmission pan gasket. I tightened it in prescribed sequence about 1/8 to 1/4 turn with a 5 inch finger wrench to little avail. Now, on closer inspection I can see that the gasket is unevenly crushed and the pan is bowed at the corner in the rear passenger side. It looks like soft metal -- any possibility of beating it back to flat or is a pan easily sourced? Prior Owner replaced the transmission a year ago and i am pretty sure it is still a BW. The pan is rectangular with 12 bolts total, 4 on each side.

Most importantly, many thanks for your help and patience with the charging system restoration. Without your help I would still be struggling!

 

Phil:

Good on you. solving an electrical issue is particularly pleasing

I am reasonably sure that the pan on the BW 66 is tin. Over tightening induces leakage as it deforms the tin around the holes that the bots go into to secure the pan to the transmission body.

I think the engine must be supported to remove that "interestingly engineered" transmssion mount! And it must be so as to drop the trans pan.

It's messy. No practical way to drain it!!!! OIly hands never bothered me. But, ATF is something else!!!

Examine the pan surface around the holes. I suspect you can see that a raised rim exists around some or all. it was over tightened. Equal pressure to the gasket is now impossible. leaks result... More is not better here...

Use a small socket as a backer and a small hammer. Tap down tht ridge and get an evens urface on the sealing edge... new gasket. Sealant optional. If used, only on the tin part, not the trans body...

Snug and a gentle pull. do Not Kill them...

Carl

 

Thank you Carl,

Verified my trans is a BW 66 and it looks like the aft mount does not cover the transmission oil pan on mine--thankfully! Also, I think that I'll try to use a pneumatic oil extractor to pull the oil up out of the dipstick. I bought one of these a couple months ago new for $60 and used it once when changing oil on a different car. Wow! fast, very little mess and should work the same for the transmission. About 20 years ago I serviced a GM trans and had to drain about 10 quarts of transmission fluid from the pan as I disconnected it, and even though I was prepared for that much fluid, it was a mess as you say. I am afraid of my skill and care in the job of flattening the transmission pan and don't see any replacement pans for sale. Say, are you a fan of gaskets or RTV type sealant? and what type gasket? I see that the torque spec for the transmission pan fasteners are only 5.75 ft-lb

 

Go for it. Not much skill needed to tap down any ridges. chances are that a used pan will also need a bit of metal work.

For that tin to iron seal, I would use a gasket. RTV works well on hard to hard. Teh exhaust manifolds on my lump are sealed with high temp RTV.

Beware, RTV excess in the transmission pan can be a problem t the tiny passages in the valve body!!!!

 

Hi JagCad/Carl,
Thanks for your advice and encouragement. The transmission pan gasket replacement on a 1987 XJ6 with BW66 was easier than I expected. Although I have a couple more checks to complete. . .
I raised the front end of the car so that I had about 8 inches between my nose and the pan. The compression nut for the dipstick was bound, but finally came off and went back on after some thread dressing. The pneumatic oil extractor worked great to evacuate about 4 quarts of ATF fluid before I dropped the pan. The pan came of easily with no need to pry it away. The pan was magnetic corrosion resistant steel and was raised and had pinched the old gasket at every bolt. I pounded the bolts areas pretty aggressively because it was visibly deformed and strong steel. Used thread on most of the bolt holes to hold the rubber impregnated cork gasket in place (gasket only cost me $5.50!). Don't have a torque wrench these days, but criss-crossed gently to a few ft-lb torque/ After initial run while on the jacks and blocks the gasket and dipstick look great! One pic is of pan ready to replace.
Many thanks!!!