Just picked up my new E-type but... got a worrying noise

[adfergusson]

So I picked up my first ever E-type today. Its a '61 flat-floor roadster. While diving it back to London the engine made a bang that sounded like a backfire while I was driving along . I was going around 65mph in 4th gear. After the 'bang' sound the engine adopted a deeper note and started to sound like it was misfiring if I pushed up around and beyond 2000rpm. I pulled over when I had the chance and had a look under the car and the hood to look for any obvious signs of damage or that I had hit something. I didn't really have any good idea of what it might be but the inspection report for the car described the engine as being very good (it was rebuilt about 800 hundred miles ago) but did point out that the exhaust would need replacement imminently. My initial thoughts were that the exhaust pipes or mufflers had disconnected from each other or the manifold somehow and that might be why the exhaust note suddenly became much deeper. Anyway, the muffler appears to still be hooked up to the exhaust pipes and they're still attached to the exhaust manifolds too.

I decided to drive the remaining miles back home. On the remainder of the trip I drove very cautiously and kept the revs under 2000rpm the whole time. The engine seemed to improve over the remaining miles although I did not push the revs to see if the misfiring would come back. I also noticed that the oil pressure was right at the top end of the scale. Initially the engine pressure of the car would rise very high when started before dropping back down a bit. After the bang the oil pressure stayed right at the top end of the scale the rest of the trip.

Before the 'bang' happened I put some more petrol in the car but I forgot to use super-unleaded and only got regular unleaded (the car has been converted to unleaded and has the stock 9:1 compression ratio as far as I know). This made me think that the misfiring may be knocking due to the lower octane. But as I've never heard an engine knocking I didn't know what to listen for. However, the car was doing just fine for quite a while and of the fuel in the tank half was super-unleaded and half was regular unleaded. I was under the impression that knocking was a problem normally associated with high compression ratios and/or forced induction engines? I also thought that knocking is also associated with higher rpms and that was certainly not the case in my situation. I assumed/hoped that its wasn't knocking and managed to make it home without further event.

Can anyone help?!

Thanks,

Alex

[adfergusson]

I'm considering buying some octane booster and dumping that in the fuel to see if this alleviates the problem? Would this be a sensible course of action

[andyp]

Let's not panic yet. My first thoughts are that a nice backfire has blown the guts out of the exhaust system. If the engine isn't making rattling or knocking noises I'd look here first.

And yes an octane booster certainly won't do any harm.

Andy

[Heuer]

Alex

My car has a 9.5:1 compression ratio and I have run it on occasion with 95 octane without problem so I do not think fuel quality is the issue. The concern is the fact the engine has only done 800 miles so any odd behaviour needs immediate investigation as a fault in re-manufacture or components may have developed. First check is to see if there is any oil in the coolant (it will have a milky look if so) as a blown head gasket is very likely. Bear in mind the head needs re-torquing down after 1,000 miles and revs should never go above 2,500 until then. For the next 1,000 miles the revs should be kept below 3,000. Not sure where you are located but may be worth getting the car checked over by a specialist.

[adfergusson]

Thanks for the advice.

I'll check the coolant for oil as soon as I get home.

I'm starting to wonder whether I might have blown a baffle in the exhaust? That would explain the change in engine note I think. I'm really hoping that its not a blown head gasket! I'm trying to convince myself that a blown head gasket would have been more dramatic than what I experienced. My bank balance has taken a big enough beating from buying the car, it doesn't need a further hit from engine repairs!

[Moeregaard]

I would add the possibility a stuck exhaust valve to the list, especially if the car has been sitting for a long time.

In addition to the excellent suggestions from David and Andy, I would also perform a compression test. Hopefully it's just a failed silencer. If the car hasn't seen much use and has a mild-steel exhaust system, it's entirely possible that the baffling has corroded and broken away. A few light blows from a rubber mallet on the silencers should reveal any loose bits rattling around in there.

[p1vickers]

Alex

As with all noises, it's very difficult to diagnose without experiencing the concern, but don't panic just yet as its already been said, it could just be the exhaust system.
If your based on the east side of London and can't get it sorted, I could come and give my opinion.

Regards

Pete

67 S1 2+2

[adfergusson]

Thanks for the advice everyone.

I've just been under the car for a quick look. I gave both sides of the middle box a knock with the handle of a screwdriver and the right side has definitely got something bouncing around in side of it. I guess that means I'll have to buy a shiny new stainless steel set! I was planning on moving to a stainless system from after the cast exhaust manifolds anyway so I'm feeling happier now that I think an expensive engine strip is out the picture!

I didn't see any oil in the coolant so I'm hoping that rules out a head gasket failure. Thanks for the offer to help Pete, thats really kind. I'm actually in west London. But I think everything should be ok now that the exhaust looks like the troublemaker.

[Moeregaard]

You could always do the modification mentioned in the factory's special tuning manual, and fit straight-through pipes in place of the silencers There will be no more rattles and your neighbours will know exactly when you're coming home!

[alfi]

Alex, now you own an etype you will find many moments of heartache, all rewarded by those fleeting moments of pleasure trust me I know from experience. Like all the best things in life no pain no gain, do the old girl a favour and give her plenty of use it worked for me I am no longer aware of squeeky brakes or burnt oil smells coming from the numerous oil leaks onto my exhaust or the gauges that read different things depending on what the weather is doing. Enjoy hope your problems a small one Alfi.

[adfergusson]

Well, I took the car to a local Jag specialist garage that I'd heard knew a thing or two about E-types (there were two other E-types there when I went in). Their opinion; blown baffle in the exhaust. I'm having the whole exhaust replaced with a Double S stainless system in the same spec as the original exhaust (1 3/4" pipe).

I intend to put hotter cams, weber throttle body EFI, big bore exhausts, ported heads, etc... and having all sorts of other goodies added to the car at some point in the future. But given that the car has what is basically a stock motor on a fresh rebuild I've decided to get to know her in her natural state with a regular bore exhaust first. I guess that when I go for all those upgrades I'll then need to go and get a nice big bore classicfabs exhaust system to match and then and try and sell the regular bore Double S exhaust. Anyone in the market for a regular bore stainless exhaust system in about a year or two?!

[Moeregaard]

Good to hear it wasn't something more internal and expensive :D !

[Car-Nut]

Alex,

Im glad you resolved the issue with your new toy

Look forward to seeing some pics in the gallery.

Like someone else said, the more you drive these cars the happier :D they are. Leave them standing and problems set in :(

Safe motoring

Clive

[p1vickers]

Alex

Glad all is well. Make sure you get to know your car and do plenty of driving before the mods, you may find it better in standard form

Safe motoring

Pete
1967 S1 2+2

[Heuer]

Alex

Been away for a few days standing around at the NEC (Call Centre Expo - don't ask) but good to get back and hear your problem was simply resolved. I second what Pete says - run the car for a while before contemplating change. As I have found out anything you 'improve' leads on to new problems and you end back where you started. Look at the number of Weber conversions that end up on eBay from disenchanted owners.