Oh MAN, Switch Holes in Chain Covers Wrong
 

I am in the process of doing a tensioner upgrade on 3.0 engine. I have a set of used timing chain housing covers that don't have holes for oil thermo-time switch in left and temperature switch in right. Ok no big deal, I'll take them to machine shop and have them drilled/tapped.

I take them to my local machine shop, along with old covers with swithes still in them and ask for them to do this.

Well, I pick them up today and when I get them home, upon inspection I find that when screwing in the switch, it threads in fine but is lopsided (it's not completely perpendicular to the cover) and that sealing washer does not completely contact the cover on one side.

I do the same with the other cover and switch and the same thing!

There is approximately .5 to 1 mm of gap between the cover and washer at 3 o'clock postion of washer, and washer is touching at its 9 o'clock position (picture taking a flat plate, placing on flat surface, and lifting up one side a little).

Will these be OK like this, or will they leak? Would some hi temp thread sealant remedy this? Should I take them back to shop and demand replacements?

I could use some advice.

-Ed

I would take them back and demand replacements. If they won't and you fight the good fight, they can re-tap larger and put an adapter in to the larger size that fits your switch.

Thanks Chris. The adapter thing is what they probably will recommend (much cheaper than covers) but it sounds like it would introduce more places to leak.

-Ed

And..in future...find a shop that knows how to tap a vertical hole!!
Bob

LOL!
The same goes for platers, powdercoaters, painters, etc., etc.
Choose your sublet contractors with care.

Thanks for the replies.

Yes, it is a lesson learned the hard way. The shop that did the work is part of an auto parts wholesale/retail operaton that was recommended by one of my clients (who owns a chain of tire & auto service centers) and does a lot of business with them. The shop has been around for 60 years and supposedly does good work.

I would really rather not raise a "stink" with the shop at this point if there is a chance that the holes will not leak - maybe some Permatex hi-temp thread sealer on them? I can post pictures of what they look like if it helps.

What's the opinion out there......will they leak or not and should I take a chance? Or should I demand replacements?

Thanks,

-Ed

A while back, I was installing a set of sway bars and since my car did not have sway bars, I was using a custom spring plate eccentic for my rear bar attachment. When I was assembing the unit, the nut stripped the threads on the eccentic rendering it useless. Since it was a Wednesday and I wanted to use them that weekend, I could not get the $65.00 replacement to me from the vendor. I took the part to my machinst and asked if he could turn it down to the next smallest size and rethread. He said no problem, it would cost me $25.00 and he'd call me when it was ready later that day. Many hours later he called me and told me that there was a problem. He accidentally cut the shaft and could not rethread it. I said not to worry, no harm, no foul. He then told me not to worry, he made a new part for me at no extra charge.

Frankly, if the machinist did poor work he should be told. I would expect a reputable shop to stand up for the work and do what it takes to correct the problem. If they choose not to, then next time, I would choose another shop.

That is the service you should expect.

Harry,

That shop seems like it has a noble attitude. The more I think about my situation, the angrier I get. I probably should take these things back and talk to the owner, try to work out a resolution......which seems like it can only be a pair of new covers.

Thanks for the insight,

-Ed

I guess he could a) make an insert and put that in straight, or b) machine the mating surface perpendicular to the threads. Neither one will look good.

Thanks PBH.

Those are options, but you're right, it just won't look right, and why should I have to suffer from someone else's mistake. I paid them to do a job, trusted their expertise when they said it was "no problem" to do (when I first dropped the covers off). After all, this is a machine shop that measures things in thousands of inches.....how hard is it to drill and tap a couple holes straight, especially since I gave them the old covers and switches as templates?

Thanks for your thoughts,

-Ed

Are you sure that the machine shop is wrong? Are the mating face and the back of the covers parallel? If I were asked to do that job I would reference of the back of the cover and drill away. Maybe the 'mating surface' is the problem, in which case I would not blame the machine shop completely...

In hindsight they should have 'indicated' the mating surface before drilling, to verify it was flat, but I would not have thought to do that.

Mating surfaces are flat. Problem is certainly taps are not perp to housing. When the switch is inserted and threaded all the way in, you can see that the end of switch "tube" inside housing is not perpendicular to housing.

-Ed

Then it definately is the machinists problem.

You need new chain covers. You will not be able to reliably seal the straight thread under this condition.

Don't despair just yet.

I had a problem a few months back when a machine shop did some minor work on my crankcase. The cases were subsequently badly damaged during return shipment, and I was devastated. I was looking at $3k+ replacement and the loss of the original cases. Packaging of the cases left a lot to be desired and I was angry at both the machine shop and UPS for gross negligence. However, I decided that yelling at the machine shop was only going to ensure a negative outcome, so I stayed calm and asked them to work with me to resolve the problem. To cut a long story short the shop reponded very positively and took the lead by lodging a claim against UPS and undertook to repair the damage to an excellent standard. As part of the repair they align bored the case, skimmed the joints and decks and supplied the necessary cylinder shims to make the whole job as good as new. They showed they are a true high class machine shop and they valued their reputation and customers.

Thought for today: Anybody can make a mistake, but true customer service can be measured by how they work with you to remedy the situation.

Give them the benefit of the doubt until they prove they don't care.

Regards
Mark Bradbury

I just looked. and those covers are sort of expensive. In my line of work we have mini disasters like this and there is always a way to fix them. In this case I would have the shop drill the holes oversize to a stock bar size. Say 1" round aluminum bar. Put a large chamfer on the drilled hole so the weld is mostly below the surface of the cover. Then have a skilled welder TIG the plugs in place from both sides. Then mill the welds and plugs flush. Re drill and tap correctly. This should result in a air tight fix and if they are good you would have a hard time seeing the repair.
A automotive machine shop may not be equipped for this but a tool and die or mold shop would have the tools and skill to do it right for you.

good luck
david 89 turbo cab

Mark, I know how you felt. I am going to call the shop tomorrow morning and do just that, giving them a chance to remedy this first.

I am still worried about welding or helicoiling these covers, as they are very lightweight and are only aluminum (or is it magnesium, they're from a Carrera and I'm not sure if they changed metals). Can they be welded succesfully, as David suggests? A loose weld or helicoil falling into the chain covers would cause catastrophic damage to the engine.

Is PBH correct in saying I need new covers?


Thanks Guys,

-Ed

I would not expect a helicoil to be air tight (or oil tight). A good welder could weld up the hole and then the things could be reworked without resorting to a plug. I would hit the yellow pages and find a welder who does TIG welding and aluminum. Explain your problem and I think you will find that it is not that bad.

Thanks a lot, David.

-Ed

i've never seen covers in the tensioner update kit, that didn't have those holes. do the covers have the holes for the tensioner to go thru, or are you trying to make your own from the old style covers?

I have some new SC\930 cam covers if you need them. They will have to be drilled for the oil tensioners .... I can have them done for you or you can find a new machinist.