omgodzilla

What would happen if I just drive with the cracked exaust manifold.
Are there any serious consequences??
WIll it damage the engine ??
Ive did alot of research on the topic and I seem to be getting mixed answers from everyone.
Some say that it has no major affect on the engine, and some say it damages the exaust valve stems creating more issues in the future..

DeathCougar

iTrader: (23)

You can damage the exhaust valves, since a crack will allow cooler air to mix with the hot air coming out. Ask any race car driver or pit man. Cracked or leaking manifolds lead to big $$$ repairs.

Uisge Beathe

I would just like to piggyback on what DC said and vouch for burnt exhaust valves...I know that one (currently) from first hand experience.

omgodzilla

deathcougar,
I called the number you pm'ed me, and asked the gentleman about the long term effects this morning.
He told me that there are no damages that occur with the cracked manifold.
He said that the only issue is poor performance..
Is this info incorrect?

CarolinaGirl

I, too, have a cracked manifold and have been told mixed stories about damage. For example, I was told it would allow cold air to be sucked in and damage the engine but since hot air expands, the minute the engine starts it would be pushinge air out, not sucking it in. Also, if a manifold has cracked, it's likely other things are starting to 'go' on the car, too, so timing could be incidental. So I'd like to know if there any engineering studies, rather than antecdotal info, that you all could direct me to?

(My toyota corolla has 225k on it, so everything is going, and whatever damage the manifold crack might might be neglible compared to everything else going on, and not worth the money to fix.)

BigBallsMcFalls

brain damage from breathing in all pre-catalyst the noxious gases. fo sho

there is a reason the exhaust is in the back

DeathCougar

iTrader: (23)

I missed this question.....

you may have spoken with Mike, who really knows nothing of vehicles. Indeed an exhaust leak can cause damage the the vehicle, even if minor.

CarolinaGirl

I meant to the vehicle. Living in the south, always driving with windows open ( dog who goes everywhere with me likes the open windows) exhaust from under the hood is not really an issue for us--but certainly for others, especially folks up in the frozen north.

CarolinaGirl

I just emailed several universities with automotive engineering departments, will be interesting to see if they have anything to say about it.

bob200587

I don't understand why this is an issue. If it's cracked it needs to be replaced. My Y pipe broke completely over the summer and the power loss was incredible. I don't see how anyone could drive a truck with a cracked pipe that far up in the exhaust system. Not to mention the deafening noise.

CarolinaGirl

Not everyone can afford to fix everything that breaks, esp. in this economy, and have to prioritize. If something doing no damage to vehicle, exhaust dangers can be managed effectively, then that lowers the priority for this repair. (BTW my crack does not result in any noise.) The correct answer is also now a matter of intellectual, automotive engineering, curiosity.

Gokumono

Subscribed.
Im really curious as to what the universities say.

KrashDH

My cracked manifold (by the previous owner) led to a burnt exhaust valve shortly after I bought it, and even DIY can cost a pretty penny. Replace it. It's simple and will not lead you down this path. I personally think its a no brainer, but if you want worse problems down the road, leave it.

Lumpy

Just as posted above...will burn the valves out. I don't think you really wanna have to start changing them do ya now? I do wonder what those smart university folks will have to say though?

Evilmunkey

More than likely UTI and a few other Auto tech universities will state it can cause burnt out valves and the chance of a bent valve due to the cool air mixing (as stated above) . really fixing your cracked manifold is far cheaper than having to replace the valvetrain, manifold, and other internal issues could arise due to this.

BigBallsMcFalls

if money is an issue there is always pole dancing


or jbweld

CarolinaGirl

I've been told so many different things, without a scientific basis for the conclusions (just because two parts fail close to the same time does not mean there is a causal relationship) so I'll wait for a response from the smart university folks are who teach the auto design engineers, based on physics, metallurgy, chemistry etc., rather than guessing what they might say, and give all of you who got it right a virtual pat on the back : ).

Evilmunkey

JBWeld FTW for a temp fix

bob200587

CarolinaGirl

or politics : ) I hear that pays well...