Mark 8 fan blown fuse

[gonein67bird]

so I put the fan in with a temp switch from checker a relay and a 30 amp fuse.I wired it like I think you are supposed to and it works for awile kicks on then shuts off kicks on then the fuse blows. I got a new 100 amp alt. but it still does it any thoughts?

[gonein67bird]

I just looked and am using a 30 amp relay. Does that matter? would a bigger relay make any diff?

[justanova]

as far as i know if you are going to use a relay on it instead of a conroller like dccontrols, then you must use a 70+ amp relay as when that fan "kicks" on it will draw some serious juice.

[matty b]

you dont need to install a 70 amp relay believe me if it drew that kind of current your car would probably die when the fan turned on. I would recommend a circuit breaker over the fuse though and if you have access to a clamp on ammeter to check the draw of the fan I would use it. I am not talking about putting an ammeter in line like normal as you will blow up the meter but a clamp on style that goes around the wire and you can see the current. Then after seeing the normal current draw of the fan you can properly size the circuit breaker. I have on occasion have had to install a 40 amp breaker on big fans so you may just be overloading the fuse. The relay you have is called a 30/40 amp relay and should be fine. If it is drawing over 25 amps once its up to speed there is an issue with the fan most likely or its bound up, the startup spike is normally what overloads the fuse though. hope this helps

[justanova]

I am aware that they dont pull that much once running but as far as the info i have read on the mark 8 fan that if used with a relay the initial spike when it "kicks" on can be in the 70-80 amp range. but I may be wrong. i know the controllers like the dccontrol start the fan softly so it doesn't get the initial surge.

[marolf101x]

Take a look at the data sheet. I used to work for SPAL in the R&D dept. so I gave Mark a call and he sent this over.

As you can see the Mark VIII fan, on high, with zero static pressure (if you don't block the fan with a radiator, but hold it in open air) pulls 25A continous.
Now, if you put it against a radiator so you have some static pressure (the fan has to "pull" the air through the radiator core), the fan on high pulls 42-43A continous.

This sheet does not show inrush current, which can exceed 70A.

In short, you need a huge alternator to run the fan and anything else; you need a 70A relay, and you need a fuse larger than 40A.

[matty b]

42 amps continuous for a single fan seems awfully inefficient especially if that chart is correct. If it trully is right then yes either a 70 amp fuse or even a fuse link wired with at least 12 gauge wiring. Personally I wouldnt use something that drew that much current though. Look at the flow of the mark 8 fan and you can see that any other fan on that chart kicks its ass. Goes to show how good FoMoCo parts are designed. Once again I gotta say that fan is not worth the trouble. You would need AT LEAST a 140 amp alternator if you arent running AC and probably closer to a 200 amp alternator to keep from overworking it. That blows my mind that it would pull that much yet flow so little.

[2yellow69]

I plan on using a mark viii fan with a spal controller. I found this article on installing one in a ford. They say it pulls about 30 amps and they upgraded to a 95 amp alternator. There is a video of the fan running on manual override and you can get a pretty good idea of airflow by the sound. If I can remember long enough (I've been really forgetful lately), I'll bring my amp clamp home and hook the fan up to a battery. I have a fan and radiator out of the car so maybe I can do some testing in the garage.

http://www.fordmuscle.com/archives/2...8Fan/index.php

Matt

[justanova]

42 amps continuous for a single fan seems awfully inefficient especially if that chart is correct. If it trully is right then yes either a 70 amp fuse or even a fuse link wired with at least 12 gauge wiring. Personally I wouldnt use something that drew that much current though. Look at the flow of the mark 8 fan and you can see that any other fan on that chart kicks its ass. Goes to show how good FoMoCo parts are designed. Once again I gotta say that fan is not worth the trouble. You would need AT LEAST a 140 amp alternator if you arent running AC and probably closer to a 200 amp alternator to keep from overworking it. That blows my mind that it would pull that much yet flow so little.

that fan kicks ass, I am using one in a 70 imp. with a dc controls controller and I have it set up with a 180* t-stat and set the controller for 180 as well and it temp sits on 180 and never moves, alot of people here including me love that fan.

out of curiosity what would you use for a fan instead of the mark 8?

[LCAC_Man]

that fan kicks ass, I am using one in a 70 imp. with a dc controls controller and I have it set up with a 180* t-stat and set the controller for 180 as well and it temp sits on 180 and never moves, alot of people here including me love that fan.

out of curiosity what would you use for a fan instead of the mark 8?

I've used the mark VIII and the smaller Taurus fans in my 4 past project vehicles and I'm using it in my current car. For the money ($30 used, $120 new) you can't touch it's performance. Siemens makes the motor assy and it's darn near bullet-proof, in "hi" that thing huffs some unbelieveable volume. You do need to run either a high power controller or 70 to 75 amp relays (bosch -156's) work real well. The shroud size works perfect with 23" wide core radiators.

[CarlC]

Hey Len! Welcome aboard.

[LCAC_Man]

Hey Len! Welcome aboard.

I saw you were a moderator here and figured it must be an ok place to hang out. Plenty of spare time here in Japan during off work hours.
Itching to get back and get some run time on that motor.

[gonein67bird]

well I got my 75 amp relay off ebay and installed it last night. Also put on a 30 amp circiut breaker. took it for a drive last night and it was working well. Thanks for the help.

[matty b]

out of curiosity what would you use for a fan instead of the mark 8?

I only use Spal fans at the shop second choice is Flexilite. If youre using junkyard parts so be it but Spal kicks ass and they have a good selection of fans that move a ton of air. Granted, Im not gonna be pushing used parts on customers for obvious reasons but even on my own stuff that is one place that I wouldnt really consider used parts. Same goes for turbos, brake parts, fuel system components and all rotating electrical components like alternators and starters. Its personal preference but all of those parts live tough lives and Ive seen those type of parts fail way to often. You can always get the lifetime gauruntee from the recycler but Im not a fan (pardon the pun) of changing out parts because they are marginal used parts.

[67 455 Bird ragtop]

out of curiosity what would you use for a fan instead of the mark 8?

I know a lot of guys who run the dual LT1 set up off a 4th gen T/A or Camaro. Especially on 1st gen f-body cars. They fit the stock size radiator and provide plenty of cooling. I plan to use this setup on my 'Bird once it's back together.

Just my .02

[justanova]

I only use Spal fans at the shop second choice is Flexilite. If youre using junkyard parts so be it but Spal kicks ass and they have a good selection of fans that move a ton of air. Granted, Im not gonna be pushing used parts on customers for obvious reasons but even on my own stuff that is one place that I wouldnt really consider used parts. Same goes for turbos, brake parts, fuel system components and all rotating electrical components like alternators and starters. Its personal preference but all of those parts live tough lives and Ive seen those type of parts fail way to often. You can always get the lifetime gauruntee from the recycler but Im not a fan (pardon the pun) of changing out parts because they are marginal used parts.

spal seems to make nice stuff, I mean ron davis uses them and he makes some of the nicest radiators ive seen. I dont use junkyard parts either, the mark 8 fan i have I bought(for my 70 chevy impala) new from dccontrol, it is an oem NEW part. In the future I may have to try spal fans but for now the mark 8 is doing the trick just fine. I have also ordered a fan from dccontrol for my dads car (70 chevy caprice) but since he had the big block I had to go with the thinner fan that i beleive is a from a taurus, is a new oem part and flows 3800 cfm(claimed by dccontrol) where the mark 8 flows 4300cfm (also claimed by dccontrol)

I have always liked the idea of using oem fans because they are designed to last.

I know a lot of guys who run the dual LT1 set up off a 4th gen T/A or Camaro. Especially on 1st gen f-body cars. They fit the stock size radiator and provide plenty of cooling. I plan to use this setup on my 'Bird once it's back together.

I havent used a 4th gen fan yet, what are the dimensions of that fan setup and do you know of a flow rating?

[67 455 Bird ragtop]

I havent used a 4th gen fan yet, what are the dimensions of that fan setup and do you know of a flow rating?

I'll give you the dimensions later this afternoon when I get home. Maybe a pic or two also. Depends on when I can get someone to help me move some stuff to get to my stock radiator. I had rotator cuff surgery 3 weeks ago and can't lift much with my left arm just yet.

As for flow numbers I haven't found anything definitive. I've heard anywhere from 2500 to 2800 cfm. But I know a few guys here in Florida and Texas (Houston) that are running BBC and 455+ pontiacs with two core alum and 4-core stock radiators with these fans and they have had no problems keep cool. I plan to use mine with a 2 row 1.25" griffin aluminum radiator that is very close to stock dimensions.

[67 455 Bird ragtop]

I did a measurement and the dimensions are 17.75 x 26.5. I'll try and get some pics on how it fits my stock 4-core tomorrow.

[marolf101x]

Now I have to start by saying I'm a little biased, as I once worked for SPAL (I'm now at air ride Technologies), but. . . you want OEM quality? Look at almost all the "exotic" cars. . .what do you see? Ferrari? SPAL; Masseratti? SPAL; Noble? SPAL; etc. Ok, so you like domestic? Buel? SPAL; Caterpillar? SPAL. (I have to note that most domestic auto manufacturers have ancient ties with Bosch or other large companies so SPAL is out of the question for them) Are the racing coolant system manufacturers more your speed? C&R? SPAL; Ron Davis? SPAL; PRC? SPAL. How about big name car builders? Troy? SPAL; (the late) Boyd? SPAL. (I could go on, but my point has been made.)

Don't get me wrong, the Mark VIII fan is a great OEM unit that one can find at a wrecking yard, or pick up on Ebay or DCControls. However, I can tell you it pulls A LOT of amps compared to a similar "aftermarket" unit. I put aftermarket in quotes as the aftermarket only accounts for a very small percentage of SPAL's annual sales withe the majority going toward tier 3 OEM sales.

[justanova]

Now I have to start by saying I'm a little biased, as I once worked for SPAL (I'm now at air ride Technologies), but. . . you want OEM quality? Look at almost all the "exotic" cars. . .what do you see? Ferrari? SPAL; Masseratti? SPAL; Noble? SPAL; etc. Ok, so you like domestic? Buel? SPAL; Caterpillar? SPAL. (I have to note that most domestic auto manufacturers have ancient ties with Bosch or other large companies so SPAL is out of the question for them) Are the racing coolant system manufacturers more your speed? C&R? SPAL; Ron Davis? SPAL; PRC? SPAL. How about big name car builders? Troy? SPAL; (the late) Boyd? SPAL. (I could go on, but my point has been made.)

Don't get me wrong, the Mark VIII fan is a great OEM unit that one can find at a wrecking yard, or pick up on Ebay or DCControls. However, I can tell you it pulls A LOT of amps compared to a similar "aftermarket" unit. I put aftermarket in quotes as the aftermarket only accounts for a very small percentage of SPAL's annual sales withe the majority going toward tier 3 OEM sales.

thanks for the info, I did not know spal was that big and did oem stuff. I am in no way saying spal isn't quality, I just have no first hand experience with them, but may try them out in the future..

I will say they do look like they have a nice advantage when space is at a premium.