Here’s the tale
Got on the road with the family to FL from VA. About an hour in, the Check Engine Light goes on. Seems to be running rough and a little rattle coming from the exhaust. The next day I put in the spare AMM and it didn’t change anything.

Upon arrival in FL, I had time to check things out. No vacuum leaks and codes 231,221,113. Signs point to O2 sensor; no way I can do that on the road. Car runs rough on startup, smells rich and a little rough running, but manageable. 1600 miles later, return home.

About a week later, the old, unknown age radiator started leaking at the seam (aluminum to plastic). Easy swap. Realized the exhaust was weird, in that I could fully cover the tail pipe while running the engine. Got under there and found holes in the axel pie and hair coming out of a hole in the 9 year old front can.

Swapped in new, reset the CEL and after over 100 miles, no problem.

Conclusion: The exhaust was clogged in the front can because the thing deteriorated inside and the hair blocked the flow.

Question: Could the rich running condition or the clogged muffler have caused the radiator to leak?

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89 240 wagon, 94 940, 300K, 94 940, 141K

Dear j.pelchat,

Hope you're well and stay so!! Question: to what substance do you refer, by the term "hair"?

An exhaust system over-pressure could - before the muffler "blew-out" - cause a weak head-gasket to fail. This might allow exhaust gas to enter the coolant. To rule that out, bring the engine to operating temperature, and see if there are bubbles in the coolant overflow tank. If nothing shows there - and you're still in doubt - have a mechanic test for exhaust gases in the coolant. The test is simple and shouldn't cost much.

Hope this helps.

Yours faithfully,

Spook

Here's a link
https://www.orlandosentinel.com/news/os-xpm-2003-07-17-0307160343-story.html

There is reference to hair-like stuff used as a sound deadener. I was pulling it out of a hole in the front can. I didn't mention that about a year ago, my wife found a fairly large clump coming out of the tail pipe. I would say enough to make a man's toupee.

There doesn't seem to be a head gasket problem. I did the other '94 a year ago due to exhaust gas in the coolant so I know they can go as they age
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89 240 wagon, 94 940, 300K, 94 940, 141K