• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

Automotice distributor cap, rotor corrosion

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

Guest
If this would fit better somewhere else, please say so.

1995 Mazda Protege, 226K miles, 1.5 liter in-line 4 cylinder engine.

I had the car for 45K miles. Has generally been very reliable and economical. First the photos:









Rotor, cap, attachment for cap (end of camshaft, I think) were all bright and shiny less than 3K miles ago. This is the fourth set of cap and rotor that has corroded, and it is happening quicker. The first time I racked it up to a long time between tune-ups. The second, to antifreeze getting inside when the cooling system was being purged of air with the radiator cap off. Green corrosion is visible, making me suspect infiltration of something. The last two times might be due to crud entering, either between the cap and distributor, or due to a faulty seal in the distributor. Various colored flecks are visible in the photos.

Systems with breaker points need a condensor to prevent arcing and buring of the points. Does breakerless ignition need something similar?

Any ideas on what to check? The Mazda distributor cap gasket will definitely be replaced.

Mazda prices are absurd. Rotor and distributor cap run about $35! Cap gasket is $12.
 
Tom, this really should go in the "Other Project" section, but I will answer you. You have a hairline fracture somewhere and it is getting worse. I would replace the entire distributor and be done with it. It is $164 at CarPartsWarehouse: distributor
 
Not familiar with this vehicle but ...... Your right that most likely gases are coming up through the distributor shaft area and condensate in the cap. Distributor seals can be a factor. But if there is enough pressure within the block to allow this it's more likely that the PCV or other vent plumbing is obstructed. Normal blow-by past the rings has to go somewhere. Even with seals compromised there should be enough draw vacuum into the intake to take care of this.
 
Last edited:
Well, if the seals of the shaft were leaking, it would be oily there, since the distributor fits on the end of the camshaft. However, it is rusty, not oily.
That particular distributor has a base that is part dielectric plastic and part base metal. Somewhere on the exterior is a crack, which is letting atmospheric air in.
 
kk, Didn't mean to dismiss the crack. I wrote the message before I saw yours and my reference to seal was meant to be any loss of integrity.
 
I understand, and not a problem. And I agree, I went there as well. I just looked around at the design of the distributor, and decided if it did leak it would be oil. As always, I reserve the right to be incorrect, it does happen to all of us, time to time.
 
When you replace smear some Vaseline or a non conductive grease between the distributor and cap to insure not getting past there.
Do not be afraid to go thick where the two halves join up.
 
I've seen this issue with old 289 Ford motors. As mentioned, bad motor evac or excessive blowby, so my viewpoint. Not sure how that much condensation would manifest itself there.
 
TooManyToys said:
I've seen this issue with old 289 Ford motors. As mentioned, bad motor evac or excessive blowby, so my viewpoint. Not sure how that much condensation would manifest itself there.
Click to expand...
Not through the path you suggest at any rate. 289 engines were pre-emission engines, so no safeguards were in place for blowby control.
You may be correct, but only continued parts replacement will find out for certain.
Best of luck, Tom.
 
A lot of times there will be a secondary plastic cover that sits over the points and condenser (pickup/ hall effect) to keep out the moisture and dust, then the distributor cap fits over it and the distributor housing. Check to see if is supposed to have one or not.

Plus there's probably an o-ring used to seal the distributor cap to the housing as well.

Similar to this... http://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/F800/image/4/

themess said:
Systems with breaker points need a condensor to prevent arcing and buring of the points. Does breakerless ignition need something similar?
Click to expand...
No. A capacitor is usually required for noise suppression only.
 
Last edited:
Thanks for the insightful replies. Next time I need help on an automotive problem, I'll try the other forum, and see how many people respond.

The rust means that water is getting inside the distributor cap. Mazda uses a fancy gasket between this horizontal distributor and its cap. It tears easily. I'm spending $15 on a replacement. I'll clean up every thing as carefully as I can, re-using the same parts. After a thousand miles or so, I'll look inside. If crud is still entering, I'll spend the $200 on a replacement distributor.
 
status

status

Not having used a timing light for 30 years, it took a while to find. So far, I haven't been able to locate the timing marks on the engine either. So I put it back together with a new gasket, or gasket plus plastic cap, referred to two messages above.



The distributor cap cleaned up nicely, but the rotor was too badly corroded to reuse. I put dielectric grease between the rotor and the distributor shaft, to inhibit corrosion. The car has been running well for several days. I'll pull the cap in a thousand miles or so to see how it looks. If any significant amount of crud is getting inside, I'll find a different distributor.

Thanks again for the help.
 
If that item on the left is the special gasket, I have two comments:
That is the source of your leak. The distributor proper should be fine.
You need to figure out why it melted on the right side. That is extremely ugly.
 
Dielectric grease goes on the tip of the rotor as well and I see your distributor does indeed use a plastic cover.
 
Thanks for clarification about what you actually meant by "plastic cover". I had imagined something that surrounds the distributor cap. Not very logical, I know. I was working long and confusing days, and had very few daylight hours a few weeks back.

I'm not sure that the original gasket melted. There is some sort of grease on it, and I don't know the source. It is also torn. It can't support its own weight. When installing, it hangs out of position. I might not have had it properly aligned between distributor and cap. The replacement gasket/cover doesn't present that problem.

I used some degreaser in the area. This should let me see if oil or coolant is coming from the outside. I'll also check the temperature in the area a few times after the engine is thoroughly warmed up, to see if anything is unreasonably hot.

It seems a bit odd that Mazda would switch out parts between the time a car is 15 years old, and 18 years old. Perhaps problems in this area are common.

Or maybe there was another Mazda part number that just happened to fit, letting them discontinue stocking a rarely sold item.
 
Good thing they changed it. I was just saying "that is the source of your leak" Hope the new one holds up.
 
Personally I don't think they changed it, but rather it was missing. You can see it's outline on the old gasket.

It's usage was quite common.
 
You must log in or register to reply here.
Back
Top