vortec 454 eating distributor caps/ rotor

[2boys1truck]

I bought my 99 k3500 with the 454 a few years back drove it daily with no issues probably 30k miles. I now have a daily driver so the truck sits a lot more and is only taken out for dirt biking, snowmobiling, hunting ect. Its sitting at 210000 miles now. About 1 year ago the motor started shaking and loss power and eventually no start it was pretty clear that it was missing very bad so i did plugs, wires, and distributor. truck seemed to run better than ever besides a little stumble at idle. 6 months later same issue but not nearly as bad. loss of power rough idle but made it home. Replaced just the cap and rotor this time and problem solved. Trucks ran good for probably 4 to 6 months, multiple trips from WA to MT and power sports almost every (weekend towing). recently i did a 3 hour drive and when i pulled off the highway I had no low end power, idle was rough but didn't die or seem like it wanted to. Made it all the way home not much of a difference at highway speed definitely low on power but was able to hold 80 home with 4 dirt bikes. I have the intake of right and was about to toss another cap and rotor at it but figured I see if anyone has experienced anything similar or possibly knew what could be going on. ask me anything for clarification forgive me I'm only 22 and not extremely experienced. thank you to anyone who replies!

 

[TexasRebel]

My 96 (vortec 4.3) was doing the same thing if I let the truck sit for longer than a week or so without being started or if it sat for a couple of days through a bad rain storm. The problem I was having was that GM did a horrible job designing the distributors for the vortec engines. They hold moisture under the cap causing corrosion inside the little tunnels that are in the cap and on the rotor. I went through 4 or 5 caps and rotors within 6 months and was getting fed up with the recurring issue. I ended up fixing the issue with mine by taking the distributor cap off and drilling a small hole in it that I put a piece of old rubber line in that would vent the distributor to atmosphere and help the moisture get out. Never had the issue again until the engine finally gave up the ghost at just under 300k miles.

 

[2boys1truck]

I've read about the venting and definitely seems like it could be the case. Where did you drill the hole on the cap and would i be better off adding vacuum or just venting to atmosphere like you said. thanks for the reply this is the 4th time I've pulled the intake I don't want to just toss in the new parts and be back here in a few months Im getting pretty quick at getting it all taken off but would prefer to not do it again any time soon.

 

[TexasRebel]

I've read about the venting and definitely seems like it could be the case. Where did you drill the hole on the cap and would i be better off adding vacuum or just venting to atmosphere like you said. thanks for the reply this is the 4th time I've pulled the intake I don't want to just toss in the new parts and be back here in a few months Im getting pretty quick at getting it all taken off but would prefer to not do it again any time soon.

I drilled mine in the side of the cap where it wouldn't interfere with any of the moving parts. A buddy of mine told me I should have teed it into a vacuum line somewhere but I didn't have any T's and didn't feel like going to get any at the time. I'm sure it wouldn't have hurt it going to vacuum but mine was fine with just atmosphere. Where I live, we see 80%+ humidity almost all year round and a good bit of rain. It's a shame that there isn't an aftermarket vortec distributor that uses a standard cap style like everything else or even a factory style cap that's already vented because this seems to have been an issue for a long time.

 

[HotWheelsBurban]

Before you start making extra holes....consider the United Motor Products blue vented distributor cap and rotor set. They have brass contacts, and the cap has a vent in it. I have these on both my trucks, '97 crew cab long bed and '99 Burb. Both are 350/5.7 Vortecs, but I live in Houston, Texas, where we always have lots of humidity. I had some issues with moisture in the distributor before I switched to this cap, but that fixed it. I can drive in a pouring rain and the truck still runs great!
I think the set runs $30-35 on Rock Auto (and no I don't get a commission from them! Just know a good thing when I find it).

 

[TexasRebel]

Before you start making extra holes....consider the United Motor Products blue vented distributor cap and rotor set. They have brass contacts, and the cap has a vent in it. I have these on both my trucks, '97 crew cab long bed and '99 Burb. Both are 350/5.7 Vortecs, but I live in Houston, Texas, where we always have lots of humidity. I had some issues with moisture in the distributor before I switched to this cap, but that fixed it. I can drive in a pouring rain and the truck still runs great!
I think the set runs $30-35 on Rock Auto (and no I don't get a commission from them! Just know a good thing when I find it).

I couldn't ever find one for my 4.3 at the time I was having the issues. I'm not even going to bother looking now as once I get my 94 going right, the 96 is getting pulled apart for a 5.3 and 4l80e. I've had entirely too many issues with that truck and it's old hacked up wiring to put up with it any longer.

 

[L31MaxExpress]

My 97 van has had the same issue since new. I vented the distributor base to a vacuum hose and fresh air hose off the intake duct. Really helped the life.

 

[Schurkey]

Failing plug wires (high resistance) or excessive spark plug gap can be really hard on distributor caps (and rotors). Don't forget to verify the plug wire resistance including the coil wire, and spark plug condition.

Vortec distributors are known for tearing up the gear on the bottom, and the bushings that support the mainshaft. Those would also be items to look at next time you have a chance.

There should be a weatherstrip at the rear of the hood, near the cowl. Make sure that's in place to keep rain out.

 

[454cid]

I've had great success with AC Delco caps and rotors. Cheaper caps are known to be short lived due to the design. I have the UMP cap that HotWheelsburban mentioned, but it's still sitting on my parts shelf.

I also have a 99 454, but with over 300K miles.

 

[L31MaxExpress]

I've had great success with AC Delco caps and rotors. Cheaper caps are known to be short lived due to the design. I have the UMP cap that HotWheelsburban mentioned, but it's still sitting on my parts shelf.

I also have a 99 454, but with over 300K miles.

That is oddly opposite of my luck, excluding the brass terminal marine caps that are all but impossible to find now. AC Delco cap did not last 6 months. The last MSD cap I had lasted years.