DeLorean Alternator Tensioner

by Chris Miles

If you’ve ever had to replace the alternator / water pump belt (or just adjust it,) you know what a pain it is – especially if you’re broken down on the side of the road! So, to make it easier, I have been using a turnbuckle style alternator tensioner. It’s made from parts sourced from McMaster Carr. You don’t need to install this now, but it’s a good idea to have it in your car, so that you can install it the next time you replace the belt. (You SHOULD have a spare belt in the car too – Gates

You’ll be replacing the existing alternator tensioner bracket (DMCT Part#: 110102) with this new tensioner. Here are the parts you’ll need to build this replacement bracket:

  1. Stainless Ball Joint Rod Ends – You’ll need to order a RIGHT hand *AND* a LEFT hand threaded one.
    1. Stainless Steel: ~$14@ – McMaster-Carr #59915K23 (
    2. Zinc-Plated Carbon Steel: ~$6@ – McMaster-Carr #2458k13 (
  2. Coupler Rod – ~$18@ – McMaster-Carr #8419K12 (
  3. Jam Nuts – McMaster-Carr doesn’t sell nuts individually, so you may be better off sourcing them locally. OR, if you really want a big bag, here are the part numbers:
    1. Medium-Strength Steel Thin Hex Nut (Right-hand thread): ~$5.50 –
    2. Left-Hand Threaded Grade 5 Steel Thin Hex Nut (Left-hand thread): ~$8 –
  4. Longer bolts – The stock bolt (Metric 8) that is attached to the engine block is 2″ long. You’ll need a bolt about 2 1/2″ long (Metric 8) to accommodate the thickness of the rod ends (which are 1/2″ thick). (Again, if you want a big bag of bolts, here’s the McMaster-Carr part: ~$9.50 –

Remember, you’ll also need a long enough bolt to go through the rod end into the alternator itself. Check your YOUR alternator bolt size, and get one about 1/2″ longer than the current size.

Alternator Tensioner |

The coupler accepts a ½ inch open-end wrench. Simply rotate the coupler to extend the tensioner, which pushes the alternator away from the water pump pulley, thus tightening the belt.

DeLorean Alternator Tensioner Parts |

I’ve been using these on both of my DeLoreans for years, and have never had an adjustment problem.

At the time of this writing, the rod ends were about $14 each, and the coupler nut was $18. The jam nuts are probably less than $1 each. For about $50, you can have piece of mind that you can replace your broken or damaged alternator belt on the side of the road quickly and easily.

Installed Alternator Tensioner |