Muffler size damages engines?

wow great responses! ok the deal is, that I am not a gear head really, but I have changed things out so I know my way around the car, having said that, I really didn’t know if the lack of power was normal or not since I had a huge dual 3" exhaust before and I just thought, “oh I guess this is what a real muffler is supposed to be like” But the muffler guy said, “you don’t need dual exhausts that is all for show and unnecessary” or something like that. And he decided to put a single muffler on it. To me the pipe looked to be like 1 3/4" and galvanized, I was irritated that he just took my two 3" chrome pipes and tossed em. So I drove around day to day stuff without ever really pushing it. No lights no warning lights nothing. oh and I got a complete tune up two days before and that mechanic said everything looked good and ran great.

I drove from the bay area to Truckee. The check engine light came on right before Truckee on 80. I drove about 15 minutes after the light came on and arrived in Truckee. The first mechanic said, you probably blew a rod. But he spent about 15 minutes on it. I had the truck towed to another town near where I grew up and dropped it at a friends reputable garage. My Dad uses him on all his vehicles. I trusted him, he has no reason to screw us. (MY father used to build and race off road Mexican 1000, baja 500, mint 400, barstow to vegas etc) The new mechanic said the same thing. But he said he couldn’t know exactly what was wrong unless he took the heads off.

But he did say that the muffler and pipes were way too small to be on this truck, and he would never install a new 454 engine with that muffler. Also, at the time of the shut off, engine oil level was fine, the transmission oil was correct level, the coolant was topped off, there were no oil leaks anywhere, no red engine or muffler. I called mieneke and asked them if they had ever heard of a restrictive muffler damaging an engine, and the said, “absolutely” I am not happy.

Thanks for all you replies.

The second place is a garage, they are in a rural area that does about 1 engine install a month. they recommended using Jasper engines from indiana.

I would strongly suggest checking the catalytic converters also. Just theory at this point but what if the converters were partially clogged and the downsizing of the exhaust from the cats back simply exacerbated the problem to the point where the engine failed?

Maybe someone could run a borescope in there and check the leading edges of the substrate in the converters. It can be common with miles, even slight oil consumption, engine tune not quite up to par, etc to cause caking on the substrate. This essentially blocks some of the holes in the substrate and bogs the engine to some degree although it may not even be noticeable.

Think of the main reason for pipe cleaners. Same principle.

To have thrown a rod and the motor is still running is very unusual, not impossible but not likely. To replace a dual muffler set with a single should mean larger diameter pipes, not smaller. Things here just don’t add up. A restricted exhaust will reduce power, but I don’t see how it results in a thrown rod.

I agree that something doesn’t add up to declare a blown engine.
There’s most likely something restricted in the exhaust, or maybe (less likely) exhaust valve damage.

Have a good mechanic check it out before replacing the engine.

I used to see all the cars that ran around with plugged up catalytic convertors,because people would cheap out and use cheaper leaded regular gas,a single muffler with enough capacity would not damage the engine,next time do not let somebody talk you into something you do not want.The hissing and blowing should have been enough of a tip off,to tell you something was wrong.

You need to provide the diameter of the OE pipe and the aftermarket.
Your vehicle more than likely came with 2.5" pipe, maybe 3".
If the replacement diameter is the same, look for a different reason the engine went south.

I’d like to know how the muffler guy got around the issues with the O2 sensors. The computer would be looking for two sensors after the cats.

I would run a back pressure test and probably disconnect the exhaust at the cat to see if she came back to life before saying the engine was dead. Then if that did not help I would do a compression and leak down test. I had a Corolla with a bad cat and it killed the power. I disconnected the cat just to get it to the shop. No damage done though.

update: Had a new Jasper engine installed, and a new dual muffler setup that has 2 1/2" pipes two new cats two new mufflers, and 3" tailpipes coming out the back. The engine ran well for a bit then an ignition wire melted, the new muffler system smoked and a few other things. this whole process has taken a long time and after all is said and done it cost me $10,000 dollars. Not sure if I am happy about the decision to do this. The suburban is still being fine tuned, and I am told that they want it to go 500 miles then change the oil and get a complete tune-up before it will be completely ready. Not liking cars these days.

Thanks for the update OP . A $10 K expense to resurrect this vehicle does seem a might steep, given that it appears all the problems are yet to be worked out. But if the remaining issues turn out not to be overly expensive or consume much of your time, $10K is a lot less than purchasing a new Suburban. Tom and Ray talked about Jasper engines in their most recent radio re-broadcast and Ray said they had pretty good luck with them. The only problem Ray could recall, one particular engine wouldn’t work, so Ray called them, the folks at Jasper apologized for the problem, and sent another engine.

I’m a bit antsy over what I’m hearing on this 10 grand expenditure. A 500 mile oil change no problem; a melted wire and the need for a complete tune-up on a new engine is another matter.

IMO dropping the exhaust to a single from a dual probably would result in decreased performance but I also think that you would have to hammer it pretty hard to blow it up with a brand new exhaust. I’m assuming that the whole exhaust was replaced at that point, really how could you simply cut off one muffler (maybe backyard but NOT from a professional shop)? With a new single exhaust, the performance will be down but it wouldn’t kill it. Also, 10 grand for the repair is really excessive, IMO. This truck is 16 years old and even at 12k a year you’re at 200,00 on the whole vehicle. Who would drop that kind of money into it? Having said all of that, is the reverse true here? A less restrictive exhaust makes an engine last longer? More questions than answers for me here, good luck anyway to the OP! Rocketman

Ray coincidentally-- in a recent NPR CT broadcast – talked about exhaust flow and the possibility of engine damage if the flow rate out the tailpipe is too fast. It was in relation to a call where one diagnostic method might be to temporarily run the engine with the cat disconnected. Ray said doing that for too long could burn an exhaust valve. Apparently a certain amount of flow restriction in the exhaust is needed to prevent burned exhaust valves.

Running without an exhaust manifold could cause problems, but I’d be amazed if disconnecting the cat would do it. So I’m disagreeing with Ray.

A properly sized,single exhaust will cut the performance ,hardly at all,especially at lower RPMs a lot of people think more racket equals more power,not necessarily,.John Ligenfelter said,only when an exhaust is really restrictive does it cut power to a noticable degree,if it sounds free flowing it probaly is,but if it is hissing,something is wrong.I bet a free flowing single 3 inch exhaust,will flow about as freely as 2.5 inch duals(but it wont sound near as sweet)

I don’t buy into the burning valves because of opened up exhaust. Air cooled engines run hotter than liquid cooled and many motorcycles have run short straight pipes (also done by me) and never had any valve issues. Race cars, air cooled VWs, you name it; many have run short straight pipes with no issues.

A lot of older aircraft also used exhaust stubs basically and suffered no valve problems. In my stash of antique, obsolete junk somewhere I’ve got an early 1950s Air Force publication about visual indentification of aircraft at night based on the flame pattern of the exhaust pipes.

My daughter had a Jasper engine installed in her 2005 Rav4 four years ago. The first one lasted only 2 weeks and had to be replaced. The second Jasper engine has surged and vibrated ever since and the shop has been unable to correct. She traded in the car 2 weeks ago. The inital estimate was $6200 but the final bill was just over $7000. So many of those Rav4 4 cyl. engines had failed that there were no used engines available in a reasonable distance.

Why did she pay such an high price for a rebuilt engine? The Toyota dealer wanted $11000.