TRExp

TR7 & TR8 Forum

TR 8 Cooling Fan Problem

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

Tom G Avatar
Tom G Gold Member Tom Graham
Shelburne, VT, USA   USA
Car has been converted to a single large fan. After some trouble shooting have discovered that I have no power to Fuses 1-2 and 11-12 the fuses that provide power to the fan relays. Relays work but since the relay is not getting power from the fuses fan does not start.

Just to be sure ran 12 V direct to fan, runs fine.

Tried to remove fuse panel to check wiring but found out that getting at the back of the panel is a real big job.

So, I am wondering if there are some connectors between battery power at starter and the fuse panel that could be faulty. The schematic shows a Brown wire running from the feed from the battery to the starter that runs direct to the fuses already mentioned. How can I physically locate and check that this wire has no problem and is actually connected to the fuse panel. A preliminary check around the area of the starter was not very revealing, hard to see exactly what is there.

This is a real mystery. Help would be much appreciated.

Tom G.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
REXUK Rex Holford
Southampton, Hampshire, UK   GBR
Check that you are getting a 12volt supply across the fuse holder ears, not the fuse itself. The fuse holder tends to age harden and doesn't make a good contact with the fuse. Rather than trying to repair the fuse box rig up an auxiliary fuse box for the fans with modern technology.

Tom G Avatar
Tom G Gold Member Tom Graham
Shelburne, VT, USA   USA
Thanks Rex; I have tried every possible way, to see a voltage at these two fuses, ears both ends as well as fuse; also cleaned up fuse ends, no luck.

Other fuses do show voltage and car starts and runs fine with every thing seeming to work well.

Yes, I am also thinking of a new fuse holder and re-wire but would really like to understand what the problem is. Overall this car is in very good condition.

Thanks much,
Tom G.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Bergie Bob Berg
Powell, Ohio, USA   USA
check the air conditioner relay switches driver side near hood hinge....I believe with a faulty relay the fans will not run on an AC car...part 8-3140 $10ea just replace......Victoria british has them...

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1500669 by Tom G Car has been converted to a single large fan. After some trouble shooting have discovered that I have no power to Fuses 1-2 and 11-12 the fuses that provide power to the fan relays. Relays work but since the relay is not getting power from the fuses fan does not start.

Just to be sure ran 12 V direct to fan, runs fine.

Tried to remove fuse panel to check wiring but found out that getting at the back of the panel is a real big job.

So, I am wondering if there are some connectors between battery power at starter and the fuse panel that could be faulty. The schematic shows a Brown wire running from the feed from the battery to the starter that runs direct to the fuses already mentioned. How can I physically locate and check that this wire has no problem and is actually connected to the fuse panel. A preliminary check around the area of the starter was not very revealing, hard to see exactly what is there.

This is a real mystery. Help would be much appreciated.

Tom G.

There is no connector between the main power feed and the fuses. But...

One must ask WHY the car was converted to a single large fan. Is it possible it was because the fuses blew, and the owner used US fuses instead of the proper British fuses? In that case, the fuse block itself becomes suspect, as it is possible to damage the fuse block by passing too much current through it.

The original fans eventually start drawing huge amounts of current because the lubricant dries out in the bearings. The fuses blow, which get replaced with the wrong kind, allowing too much current to flow. The fans work for a while, but then either the wiring burns, or the fuse box gets damaged.

So, the owner replaces the fan with a single large fan, and wires it to who knows what.

OK, so start by tracing the wiring to the fan. Does it indeed connect to one or both of the relays?

Next, make sure the fuses are not bad by checking them with a meter (not a visual inspection). If too much current gets passed through the fuse box, the fuse clips get hot and the fuse opens at the end, where it is hidden by the metal cap on the end.

Make certain they are the correct type of fuse. British fuses are metric, US fuses are SAE. British fuses are rated for the guaranteed to blow current, US fuses are rated at their guaranteed maximum current WITHOUT blowing. So US fuses will pass nearly twice as much current as British fuses before they blow. US fuses are also about 0.050" longer than their British counterpart. IIRC US fuses are 1-1/4" long, so British fuses will be just a tiny bit shorter.

OK, still having problems? I think you are looking at pulling and inspecting the fuse box. Power to the fuses that are unswitched (and the power to the fans is unswitched) is supplied from two fat brown wires, and you cannot see what is going on without pulling the fuse box. From there the power goes to the relays.

If you check everything, and there really is no power to those fuses, then I really don't see an alternative to pulling the dash to get at the back of the fuse box to look for damage.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
The main power feed runs along the passenger rocker and up the passenger footwell. Before it hits the bottom of the dash level there is a black plastic cover on the main power cable. Under that cover is a spliced in terminal connector that said brown wire connects to. Chances are it is loose or even got kicked off. Be very careful thou that it wasn't removed on purpose. The stock fans are prone to wear out and draw enough power that they melt the wire going from the fuse box up thru the passenger fender and on to the fans. About 3 summers ago I had to pull that whole section of front harness and rewire not only the fan wires, but also every wire that was in contact with them inside the wire bundle. This was on a friends car that had been modified with a 4.0 and no longer had AC, so it gave us a chance to simplify the harness and also to make a new engine harness that better served the new aftermarket engine electronics. Took a weekend to figure it out and another to fix it, but at least his car didn't burn to the ground.

Tom G Avatar
Tom G Gold Member Tom Graham
Shelburne, VT, USA   USA
Todd,

Your post proved very helpful. I found the connector exactly where you said it was,just had to roll back the carpet. Every thing seemed to be tight and in place. So this does not seem to be the problem. HOWEVER, in th at same area I found a length of loose brown wire attached to a none original spade type fuse holder. The other connected wire was a purple with white strip. The 30 amp fuse was melted and one of the c onnecting wires showed a heat issue adjacent to the fuse holder.
T
I tested the brown wire for 12 Volts and sure enough it showed battery voltage. The purple white strip wire showed no voltage. I tested to see if it was grounded but no. Not with the ignition off anyway. I reconnected the wiring as it was with the rad heat sensor shorted out, cut out the melted fuse holder and joined the wires (Brown with the purple with white stripe), Turned the ignition on and fan started up, no problem (still no voltage at fuses 1-2 and 11-12 but I checked that with fans not running. Perhaps if I check with fans running I might see something, perhaps from the energized relays which had gotten 12 V from some source not yet identified.

I checked the amps with my VOM and showed almost 10 amps; something like 9.8.

So, I am thinking about using a 15 amp fuse.

Also, so; am thinking about declaring victory though still a little concerned about why the 30 amp fuse melted. I will probably put it back together and see what happens, presuming the 15 amp fuse will prevent any disaster. If the fan dies, the car runs nice and coolwithout it as long as you are moving. I live in a rather rural VT area so can usually avoid traffic. Obviously this is not my daily driver as I have (including my wife's car) two dailies plus my little TF Victor and an E-Type OTS.

Thanks again for your help as well as to the other guys who took the time to comment.

Tom G.

PS and BTW I cannot on my schematic find a purple wire with a white strip anywhere, at least not associated with the cooling fans.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Here is a diagram that shows the two purple wires coming directly off the fuses and heading up to the fans. They are located top center of the diagram. Those circles in the circuit symbolize the connector inside the engine bay.

http://www.team.net/TR8/tr8cca/wedgelab/other/schematics/TR8_schematics.pdf

Don't hook them up directly. They need to run thru those fuses that blew. The longer those fans spin, the more resistance is built up in those wires. More resistance more heat. Eventually they will melt the insulation exposing the wires to corrosion and more resistance. Eventually the fuse will blow, but that may take years. Remember, those wires are in the center of a bundle of wires. No way for the heat inside the wires to escape. Once the smoke is let out of a British wire, your all done.

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1501177 by TR8todd Here is a diagram that shows the two purple wires coming directly off the fuses and heading up to the fans. They are located top center of the diagram. Those circles in the circuit symbolize the connector inside the engine bay
.

The only purple wires I see related to the fans are Purple/Greens stripe, and Purple/Pink stripe. There's a Solid Purple that's always hot and powers such things as the cigar lighter, courtesy lamps, trunk light, clock and a couple of miscellany. There is a White/Purple stripe wire that has to do with a power antenna.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Tom G Avatar
Tom G Gold Member Tom Graham
Shelburne, VT, USA   USA
Hi Todd,

I checked the diagram you attached and see the two purple wires but one has a green strip and the other a purple strip. Peter Wirth has joined the conversation and he mentioned the same wires. BTW I have the same diagram and, I think; if so it is a vector based graphic and blew up crystal clear at about 3 X size at Staples at about $1.86 per print. Much easier for these old eyes to follow.

I believe the fan work on this car was done at the Wedge Shop but only because I know the PO had a lot of work done there. Perhaps the purple w/white stripe wire s was added when the fan was installed.


Today I had the idea that perhaps there might be (with fan running) a feed back through the Brown (N) wires to the 1-2 and/or the 11-12 fuses. Did a test but no voltage at either end of the fuses/ears.

Last night I spliced in, (joining the newly located N and PW wires) a new fuse holder for ATC blade type fuses, (to replace the melted one with the 35 amp fuse).

As I already mentioned I had measured the amps at this location (with fan running) the peaked at a little over 11 at start-up and as mentioned just below 10 while fan is running (Mardyne fan). Having done a lot of research lately on British vs American fuses (American should be about 40% less to be equivalent) I decided to try a 10 amp ATC fuse. Fan did not run!! Took me a few minutes to realize that the fuse had instantly blown. Went to a 15 amp fuse and it seems to run happily.

This experience seems to indicate that the ATC fuse ratings are no as conservative as the old American glass type. Perhaps as they a also widely used in European cars as OEM the standard is different. Someone might want to comment on that.

Have tidied every thing up, the ATC fuse holder is easily accessible just under the edge of the dash and there is a supply of 20 amp fuses in the glove box just in case; but I hope the 15 amp fuse does the job.

Note that the it seems that most fuse holders come equiped with #12 wire; the N and Pw wires I connected appear to be #14 which should be OK for around 10 amps. Unfortunately Butt Connectors do not seem to be available for splicing #12 to #14. I customized a coule of 16-14 AWG connectors, enlarging one end to suit the #12 wire.

Will do a test run today.

Again, thanks to all for their comments

Tom G.

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1501149 by Tom G
I checked the amps with my VOM and showed almost 10 amps; something like 9.8.

So, I am thinking about using a 15 amp fuse.

Also, so; am thinking about declaring victory though still a little concerned about why the 30 amp fuse melted.

Tom:

Be careful. As I stated, British and US fuses are very different in behavior, if not appearance. The 30 amp fuse, if it is a British fuse, would roughly be equivalent to the 15 Amp US fuse you are considering.

BTW, those cheapie in line fuse holders can get quite hot, as they have a significant voltage drop when they are asked to pass more than a few amperes. If you are going to pass some serious current through there (and 15 amps is serious) then you will not want to use it if it is one of those cheap nylon in line fuse holders. The fuse will blow, not because the current rating of the fuse is exceeded, but because the holder will get very hot, and heat the fuse to the point where the link melts, even though it is not exceeding it's rated current.

Those in line holders are really only good for lower current loads, for a radio or interior lighting.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
I'm guessing the original twin fans failed and blew some fuses so the Mardyne unit was installed. Even if the wrong fuse and holder was used,I don't know why The Wedge Shop or whoever did the job did not locate the splice at least in the area of the original fuse box location. The Purple/White has to be whatever what was laying around because that combo is not used anywhere in a TR8. It may be splitting hairs but it is significant that the power antenna wire is White/Purple, not Purple/White, meaning the dominant color is White with a thin purple stripe as the trace. Assure yourself the hot brown wire is either original or at least is professionally connected to it's power source and not with just one of those cheesy blue plastic quick splice things.

Tom G Avatar
Tom G Gold Member Tom Graham
Shelburne, VT, USA   USA
Vance,

The fuses I used for this are the spade type and I think perhaps do not have the same issues as the American made glass type relative to the current flow at which they blow. Not sure, will try some new more searching on the internet.

Thanks,
Tom G;.

Tom G Avatar
Tom G Gold Member Tom Graham
Shelburne, VT, USA   USA
Peter,

I'm thinking the same same thing. As far as I can tell no sign of those blut plastic things, only reason to use those is for wiring a trailer light hook=up.

I often buy this electrical stuff at West Marine or similar place. The boat stuff is often better quality.

Ran the car this PM, fan cuts in just past mid point on the gauge and turns of after a drop of just about one indicating needle width. The fan start current inrush seems higher than expected, it immediately blew my 15 amp fuse, also a 20. A 30 seems to be doing OK. No sign of any significant temp rise in the wires. Cannot detect any using the finger touch method.'

Thanks,
Tom G.

Tom G Avatar
Tom G Gold Member Tom Graham
Shelburne, VT, USA   USA
Note to Triumph Forum 12/5/2017 GENERAL INFO Re Electric Cooling Fans

As I think I have mentioned I ended up with a 30 amp fuse while testing the car with engine running; 20 and 15 amp blew almost instantly at start-up.
All motors of this type (and most all other DC motors) have a high “inrush” current at start-up; this declines quickly as the motor speeds up and begins to develop what is called “back-EMF”. The motor generates a voltage that opposes the voltage applied to the motor. AT speed as you load the motor it slows, the opposing voltage decreases and there is an increase in current flow to the motor and more power to handle the load but speed will be lower. AC motors a different story) (basic electrical engineering to which I was exposed many years ago).

Wanting to find out more about the Mardyne fan relative to the above discussion I called their Tech Support (1-800 403-7953) and talked to Gerry Eubanks about all of this. The Mardyne I have is I believe a M142K, 14” Diameter that is rated at about 17 amps (at operating speed). At start the fan has quite a bit of inertia to overcome (large diameter) so I expected the start-up amps to be high but a little shocked when Gerry said; “all that your system could supply”. Next question then is, how does the fuse deal with this. Well fuses are designed with this issue in mind and a somewhat oversize fuse can deal with this given that peak flow is probably only for hundredths of a second, assuming fan is in good mechanical order). This also preserves the wiring.

Gerry said that they recommend a 30 amp fuse for this fan. A 25 might also work. He also said they recommend #12 wire. The TR8 wire is at most #14 but should work if fan is in good shape. Gerry was very helpful, but if you talk to him you should know the Model # of your fan (there is a label on the back of the motor).
Not so much info about this data on the Net, perhaps because it is found in SAE and EU standards that you have to buy.
Hope this is helpful.
Tom G.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster