Coil pack questions - should they have cracks?

[scot850]

I am working on the replacements, but first have to sort the faulty axle issue from Erie Vo-Vo.

Neil.

[abscate]

Look at the date codes to see how old they are. They do last 100k plus, so if they have been replaced.

My 1999 got all new ones at 140k, jim had put two new ones on the 2005, I replaced the other 3 and sold off the used 6 spares, keeping one spare for each car to cover over half the nut.

[scot850]

I have contacted several on-line advertisers of used coils, and they all say the same that what they are selling are all cracked in the same areas. Don't see the point of buying more stuff that may or may not work. I have bought another new set of OE from Swedish Auto Parts for an excellent price.

Neil.

[cn90]

Sure, nothing wrong with buying new, each Bosch coil is roughly $45-$50, so $50 x 5 = $250 is still a good price.
Sometimes we think these cars are old and not worth putting in $250, but I think it is worth it, still better than a car payment.

Four new tires cost even more...

PS: if this were my car, I would leave it alone, as long as there is no misfire or error codes, it is fine with me.
Leave the cosmetic cover off, it traps heat.

[scot850]

Actually paying in that region for OE Volvo coils + Shipping!

I've been trying to research if these modern coils use oil as a cooling agent like the old coils on distributor engines. So far all I can say is they don't appear to, they are 'potted' which wouldn't allow that I believe.

The question then is what was the brown residue around the rubber boots on the coil packs? All I can think of is at some pint oil got to them somehow and that is just residue. The reason I struggle to believe that is it was even on cyl #5 which is a long way from any obvious oil source.

So if there is no oil in the coils, then why do they crack on the bodies and why on my small sample are the all cracking in the same 2 places? I know plastics can 'dry out' in hot temperatures and become brittle and shrink which I am assuming is the cause of the cracking. Why in the same places? Must be something in the design. Now I know the rubber boot should shield any energy loss from occurring as the cracks are inside the boot.

I did some research on the internet and people have used high temp epoxy to seal the cracks and in some cases seal all the way around coils to prevent further cracking and it has worked as long as the epoxy is high temp and sticks to plastic.

I might try to find a suitable epoxy to fill the cracks and see what happens. Biggest issue is I will need to keep a car long enough to find out!

Neil.

[mecheng]

Maybe the goo is some of the wire insulation is melting off, although if it was severe you would have shorts in your coil.

If one coil goes out, it doesn't strand you, I would seal it and forget it.