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TR2/3/3A The Newest Bug to Fix...Now with Video!

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M_Pied_Lourd

M_Pied_Lourd

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Maybe have a jumper wire ready for when the fan kicks on.... jumper from the pos on the coil to the batt to see if the coil is losing +12V. It would be interesting to see if it starts to idle better when you jumper the coil.
 
Nice. I think Randall has a great idea -not that he generally doesn't.

Your "test" video is different from the last "test" run because the hood (bonnet) was open the whole time. I think the air intake temperature rising is causing the drop in idle. Your ammeter goes to discharge when the fans come on, which should be expected. I'm not sure where your alternator "cuts in", but raising the idle a little might keep it charging all the time. (I have my idle set to about 1,000 so I never get a discharge.) But I don't think your problem is electrical.

Anytime I run my car in the garage, I put a box fan in front of it to bring in fresh air. I think if you ran your same test again, with the hood closed, your car would shut off sooner. Hot air being sucked into the carbs acts differently than cold air being sucked in. And I assume the temperature of the fuel coming in also has an effect. A closed hood would allow the carbs/air to warm quicker.

I think I'd try running it without the alternator connected, and you might find it does the same thing. -That doesn't prove you don't have a bad coil, or the problem is not electrical, but I think your efforts would be better spent looking at ways to keep the fuel cooler. Do you have a way to measure the temperature near the carbs?

It gets warm here in Texas. One of the things I did was replace that fuel line from the pump to the filter/carbs with a larger line. I had trouble with that goofy sized feral leaking and it was simpler to go with a larger sized pipe/fitting. Also, I see your fuel line goes really close to the front of the block. Mine is farther away. I've heard of people putting wooden clothes pins on the fuel line to act as heat sinks, but that seems a bit silly.

Interesting problem. I'm guessing that if you had a volt meter attached to the input side of the coil, you wouldn't see a significant change until the car stalls.

I know I'm sort of rambling, but I like sharing your problem. If I knew, I'd tell you what was wrong.
 
Thanks guys.

It's a puzzler to be sure :cool:

For sure, the problem is magnified with the bonnet closed and no air coming in through the rad. If you recall, I took it for a spin yesterday and even with the car moving and not stopped in traffic for any extended period of time, I still had the same issue.
I do have an infrared thermometer and I'll take some temperature measurements tomorrow. I have ordered an ARE heat shield to help with the heat from the header/etc.
I did run the fuel line in the stock location and I did make sure it has rubber insulation on the bracket underneath the thermostat housing. Fuel lines seem to not to be overly warm to the touch. If you notice, I took the glass filter out as that seemed to be getting heated by the warm arm from the fan.

We will figure it out eventually...just hope it is before the snow flies!

Cheers
Tush
 
Hi,

I believe I had the same problem. In my case, the mechanical advance in the distributor was moving from about 5 BTDC to about 10 ATDC. Its easy to check with a timing light. You can also pop the cap off and check by twisting the rotor. It should return to were it was. If not, time for a new distributer or a rebuild.

I had the Lucas DM2 distributer, which I have read has this problem. The D25 that replaced it has a better mechanical advance.

Good Luck, RG
 
Thanks RG, timing and advance has been checked. Also swapped distributors to be sure. Doesn't seem to be the problem.

Cheers
Tush
 
I'm gonna make a wild guess and say it's the coil overheating. The clue was when you said the fan is bringing hot air into the engine compartment; looks like it's blowing right on the coil.

Thanks for documenting all this; I'm sure you're contributing a great deal to the knowledge base!

:cheers:
Mickey
 
Tush, I've had some coils do some really weird things and it could be a coil problem. I have a question for you, about how long does the car have to set with the engine off before you can start it up and it runs okay after it has shut down?
 
Tush, I see you said you are going to get an ARE heat shield. I added one of those to my TR3. In researching about the carb heat shield I found that it is highly recommended to apply a couple of layers of heat shield material to the backside of the ARE shield to prevent it from getting just as hot as the manifold. In my case I bought a couple of sheets of Thermo-Tec stick on heat shield and put on two layers on the ARE shield once I had the ARE shield fitted to my car. I found that I had to modify the ARE shield to fit.
As I recall this is what I used>> https://www.thermotec.com/products/14001-aluminized-heat-barrier.html
Regards, Bob
 
Definitely sounds electrical. As a test. try putting ice cube bag on the hottest part of the fuel system to see if that helps. It probably won't. I'm no expert but do you have a relay for the fan? If not, is it needed? A better question - was it running fine with the present setup before it started acting up? or did you do something or add something and then hit the problem?
 
I would say voltage drop to the ignition from the fan running. My Saab dies like that when I roll down the window. Perhaps at that nice low idle the alternator is not delivering the power.
 
TR3TR6 said:
Tush, I've had some coils do some really weird things and it could be a coil problem. I have a question for you, about how long does the car have to set with the engine off before you can start it up and it runs okay after it has shut down?
Click to expand...

Hi Terry. Probably needs to sit for about 5 minutes or so to start just on the key with no throttle input. I can usually get it to start again right away again if I give it some throttle when turning the key although it will run rough...

Cheers
Tush
 
TuffTR250 said:
Tush, I see you said you are going to get an ARE heat shield. I added one of those to my TR3. In researching about the carb heat shield I found that it is highly recommended to apply a couple of layers of heat shield material to the backside of the ARE shield to prevent it from getting just as hot as the manifold. In my case I bought a couple of sheets of Thermo-Tec stick on heat shield and put on two layers on the ARE shield once I had the ARE shield fitted to my car. I found that I had to modify the ARE shield to fit.
As I recall this is what I used>> https://www.thermotec.com/products/14001-aluminized-heat-barrier.html
Regards, Bob
Click to expand...

Thanks Bob. Did you add a second set of insulators as well? I'm wonder if I need to...I suspect that the studs will be too short to mount the carbs on the manifold if I do...

Cheers
Tush
 
sp53 said:
I would say voltage drop to the ignition from the fan running. My Saab dies like that when I roll down the window. Perhaps at that nice low idle the alternator is not delivering the power.
Click to expand...

New video coming up in a few minutes...just uploading...doesn't look to be the issue (although I kind of wish that it was :cool:)

Cheers
Tush
 
pdplot said:
Definitely sounds electrical. As a test. try putting ice cube bag on the hottest part of the fuel system to see if that helps. It probably won't. I'm no expert but do you have a relay for the fan? If not, is it needed? A better question - was it running fine with the present setup before it started acting up? or did you do something or add something and then hit the problem?
Click to expand...

Yes, the fan has a relay installed and is thermostatically controlled, but I also have an override ON installed under the dash.

It's been an issue since getting it back on the road..I didn't buy the car running and didn't drive it before the restoration began..I can tell you that the car came to me with the header that's on it now installed as well as the carbs. It also had an electric fan and stock rad...I've upgraded to an aluminum rad with a SPAL electric fan installed . I'm beginning to wish that I had a pusher fan installed rather than a puller...

Cheers
Tush
 
Evening All,

Ok, more tests done tonight. Ruled a few things out but that's about it :cool:...

https://youtu.be/BpYPdLTR-1w

Look forward to reading your comments.

Cheers
Tush
 
Hi PB

Yes, the jets look good.

Cheers
Tush
 
Tush, I used only one carb insulator with my ARE heat shield. I put it on the intake manifold side of the shield, so the carbs then went directly against the heat shield. I did not think of putting two carb insulators. That extra thickness might affect air/gas flow into the manifold from the carbs, but that may not be a problem. The only other problem with two carb insulators is that there is not much clearance between the front air filter and the inner fender with one insulator so two would put it really close. Putting an insulator between the carbs and the heat shield seems like a very good idea. I will have to think about doing that.
Regards, Bob
 
TuffTR250 said:
Tush, I used only one carb insulator with my ARE heat shield. I put it on the intake manifold side of the shield, so the carbs then went directly against the heat shield. I did not think of putting two carb insulators. That extra thickness might affect air/gas flow into the manifold from the carbs, but that may not be a problem. The only other problem with two carb insulators is that there is not much clearance between the front air filter and the inner fender with one insulator so two would put it really close. Putting an insulator between the carbs and the heat shield seems like a very good idea. I will have to think about doing that.
Regards, Bob
Click to expand...

Hi Bob,

Thanks for the reply. Yeah, I was thinking that and extra two insulators might be a problem for the issues that you point out. It does suggest that you need to use 4 insulators total on both the ARE site and the Moss site so that's why I was asking.

Cheers
Tush
 
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