Exhaust sounds different

[mr_maxime]

I've noticed that the exhaust started sounding different. Best I can hear it from is right behind the driver's seat. Only thing I've done recently is change from Castrol GTX to vr-1. I'm worried something might have come loose or broken.

https://youtu.be/HKcYTq7YXtI

[Bob635]

You might want to watch the video documentary on what happens to your Delorean as it ages 35 years.

Bob


I've noticed that the exhaust started sounding different. Best I can hear it from is right behind the driver's seat. Only thing I've done recently is change from Castrol GTX to vr-1. I'm worried something might have come loose or broken.

https://youtu.be/HKcYTq7YXtI

[David T]

You might want to watch the video documentary on what happens to your Delorean as it ages 35 years.

Bob

Check for exhaust leaks. The exhaust manifold gaskets commonly blow out.

[mr_maxime]

That's kind of what I figured. I couldn't think of a way of easily checking it though.

[opethmike]

Definitely a bad manifold gasket.

[David T]

You can tell by the sound if you have any experience. Other ways include looking for black sooting, feeling for air movement, missing nuts, etc. Basically if you think it is leaking it probably is. Another thing to check is the bonding of the rear window at the bottom, center. Press on the fiberglass. If it moves it is no longer attached to the glass and that lets in a LOT of noise. It can be one of the most fun jobs to do on a car. High probability of breaking the studs if you don't know what you are doing. My favorite way is to heat the nuts up to cherry red and let them cool. Heat a second time and then carefully unscrew the nuts. Works 99% of the time. Figure on resurfacing the manifolds. Only a machine shop can do that but it isn't expensive. You should also replace the studs. PJ Grady has a S/S kit. Expensive but well worth it for the next time! If you don't have a torch you should probably let a shop do the job. Pre-arrange with them so you can supply the parts, a gasket set and the studs and nuts. Verify they will send the manifolds out to be ground flat, that is important so the gaskets don't blow out again soon. The studs are metric so you will not be able to source them locally and the gaskets will be better than you can find locally if you get them from a D vendor.

[mr_maxime]

How critical is this to fix? The Delorean is my only car at the time so time consuming repairs like this aren't easy to do. I also don't know any shops nearby that could do it. I might have to arrange a trip to either dmch or dmcfl.

[David T]

[QUOTE=mr_maxime;210905]How critical is this to fix? The Delorean is my only car at the time so time consuming repairs like this aren't easy to do. I also don't know any shops nearby that could do it. I might have to arrange a trip to either dmch or dmcfl.[/QUO

The leaking and noise will get worse over time. Eventually it can damage the surfaces of the cylinder head by erosion. If you let it go that far you have to remove the heads and get them resurfaced as well, a much bigger job. In most States you will fail inspection. Any good shop should be able to do this job in a day or less.

[DMCMW Dave]

[QUOTE=mr_maxime;210905]How critical is this to fix? The Delorean is my only car at the time so time consuming repairs like this aren't easy to do. I also don't know any shops nearby that could do it. I might have to arrange a trip to either dmch or dmcfl.[/QUO

The leaking and noise will get worse over time. Eventually it can damage the surfaces of the cylinder head by erosion. If you let it go that far you have to remove the heads and get them resurfaced as well, a much bigger job. In most States you will fail inspection. Any good shop should be able to do this job in a day or less.

I don't think I've EVER seen heads damaged due to this to the point of needing to be resurfaced. The manifolds, however, must be resurfaced any time you do this job.

If you take it to a local shop be really sure that they know what they are doing. Don't let them take shortcuts such as skipping the manifold resurface or only doing one side. Make sure that they are comfortable extracting broken studs and doing thread repair in blind holes. If the job is done incorrectly it won't last very long. If they run a drill or tap through a stud hole in the head you'll end up with coolant or oil leaks.

[mr_maxime]

Finding a good shop that I trust isnt all that simple. Iwouldnt be surprised to find someone that claimed to know what they were doing and didn't.

[David T]

[QUOTE=David T;210907]

I don't think I've EVER seen heads damaged due to this to the point of needing to be resurfaced. The manifolds, however, must be resurfaced any time you do this job.

If you take it to a local shop be really sure that they know what they are doing. Don't let them take shortcuts such as skipping the manifold resurface or only doing one side. Make sure that they are comfortable extracting broken studs and doing thread repair in blind holes. If the job is done incorrectly it won't last very long. If they run a drill or tap through a stud hole in the head you'll end up with coolant or oil leaks.

Rare to see erosion on the heads probably for 2 reasons. One, most Deloreans don't get that many miles on them and two, the noise becomes so annoying that you won't let it get that bad. With cast iron manifolds and aluminum heads, the heads will take the brunt of the erosion.
As for all of the caveats of being careful, any good shop should be able to do this, none of it is peculiar to Deloreans. It all depends on what "good" means. Good means a shop that has done this kind of work before on other make cars of similar design (cast iron manifolds and aluminum heads). One way to find a good shop is to talk to other owners of classic cars. In any big city there is usually a "go to" place that everyone knows by reputation. If you really can't find a place then you are stuck having to travel. Do NOT choose a place by price, pick a place based on quality. It will cost you a LOT more than what you could save if the job gets screwed up. Even if the job gets screwed up all is not lost. It just becomes a bigger job since you will remove the cylinder heads and either repair them or replace them.

[mr_maxime]

Found a well reviewed mechanic that referred me to another shop named Hesco Automotive which specializes in classic and exotic cars. They told me they could do this job and replace my leaking crankshaft seal. I ordered the complete SS kit from PJ grady since I have an aversion to putting any plain steel back onto the car.

[mr_maxime]

It was not the manifold gaskets. I had a fairly hefty labor bill to have them done which included drilling out some bolts connecting the exhaust together as well as getting my crankshaft seal done. Granted, I couldn't have avoided the a lot of the labor considering they had to remove parts of the exhaust to do the crankshaft seal.

Anyways, it is the front pipe (https://store.delorean.com/p-6453-front-pipe.aspx) that's leaking. Hindsight is 20/20 but it really sucks to have been stuck with such a massive bill without fixing the problem and not being able to use those labor dollars towards a performance exhaust.

[David T]

It was not the manifold gaskets. I had a fairly hefty labor bill to have them done which included drilling out some bolts connecting the exhaust together as well as getting my crankshaft seal done. Granted, I couldn't have avoided the a lot of the labor considering they had to remove parts of the exhaust to do the crankshaft seal.

Anyways, it is the front pipe (https://store.delorean.com/p-6453-front-pipe.aspx) that's leaking. Hindsight is 20/20 but it really sucks to have been stuck with such a massive bill without fixing the problem and not being able to use those labor dollars towards a performance exhaust.

So much for a "well reviewed" mechanic. He should have been able to tell if it was a manifold gasket or a pipe leaking.

[eight8toy]

May I ask how much the labor bill came out to for the main crankshaft seal? I'm currently trying to tackle mine and was curious if it was worth the trouble. I really need an impact wrench!

[mr_maxime]

So much for a "well reviewed" mechanic. He should have been able to tell if it was a manifold gasket or a pipe leaking.

To be fair, I told him the gaskets were leaking and to replace them. It was after they took it for a test drive that they noticed the leak was actually from the front pipe. I should have told them to inspect it first.

Main crankshaft seal labor came at around $530 including associated labor. It was $117.18 for the seal and sleeve alone if you tow it in with the fascia and exhaust removed.

[mr_maxime]

Here was the damn problem
https://i.imgur.com/hesZxxT.jpg?2

[DMC5180]

I have too say, that’s the first time I’ve seen that bellow joint fail. I always wondered how long they would hold up. I’m sure the shops that work Deloreans full time, see it on rare occasion but don’t talk much about it.


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[David T]

Because they so rarely fail, my guess is that at some point in the past that joint was damaged by mishandling. Is there any history of work done on the exhaust?

[mr_maxime]

I hadnt seen any in the paperwork I had. Unless the shop broke it during the gasket job I had done, I can't see a specific reason how it would have been mishandled before that.

Other thing i can think of is the time I drove over a chunk of semi tire. It bent a horn bracket and someone knocked the ignition coil wire out of the connector. May have also hit the exhaust.

[DMC5180]

I hadnt seen any in the paperwork I had. Unless the shop broke it during the gasket job I had done, I can't see a specific reason how it would have been mishandled before that.

Other thing i can think of is the time I drove over a chunk of semi tire. It bent a horn bracket and someone knocked the ignition coil wire out of the connector. May have also hit the exhaust.

Not likely, that’s a fatigue fracture from heat cycling. The cylinder head exhaust studs are famous for thermal fracturing especially on the cylinder ports closest to the crossover pipe. Both of my forward studs were broken when I got my car 25 years ago. 30k on it then. If the crossover pipe slip joint becomes frozen, the thermal expansion of the pipe puts undue stresses on those forward most studs.


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