Noise! not sure what is is - help

DaviesDJ · Post by **DaviesDJ** » Thu Dec 12, 2013 6:52 pm

Dear all
My 5.0 litre rv8 Landy (2 bolt main, top hat lingered block- tvr balanced rotating assembly- stage 3 heads - Eddie performer manifold- occasional nos) has been running really well recently but within the last week has developed a perchlorate sound. From within the car it sounds like a rapper- but under the bonnet it sounds gaseous - like gas rapidly being pushed out of a small hole - it occurs at engine speed at the same frequency as a cylinder firing. When you stop the engine the noise elongates and hisses and the engine comes to a half. I have recorded it to send as an email to anybody who thinks hey can help. It is coming from the drivers side bank, and I took the exhaust manifold off and replaced them using fire gum and new gaskets, thinking it was a leaking exhaust manifold gasket but this did not improve. The engine is running smoothly otherwise; and idles well- at higher revs it is less obvious and is quieter at startup. I think it is a little down on power, but I am a little reluctant to test it on a power run when it makes this noise. It appeared while driving normally. Any ideas?? I intend to do a compression test to check if its a cylinder head leak - but sure if a cylinder was blowing it would cause overheating or other symptoms- but am not 100% sure. The exhausts are covered in wrap and could it be possible that this is a hole in one of the primaries??? But the his reminds me of the sound you get when turning an assembled engine over with the pugs in- only much more frequent obviously. Really want it ready for the end of jan so all help appreciated!!

JSF55 · Post by **JSF55** » Thu Dec 12, 2013 7:20 pm

If it's anything like mine it's probably a blocked breather, I had fun finding it too !

DaviesDJ · Post by **DaviesDJ** » Thu Dec 12, 2013 7:35 pm

Ahh- blocked breather! Could be- I simply have a small filter on top of my flame trap- how did you find that? And was the noise you had regular and in time with the engine? Would have thought that would be a constant sort of whistle sound?
Cheers
Dave

ppyvabw · Post by **ppyvabw** » Thu Dec 12, 2013 8:40 pm

My humble, for what it's worth.

I had a breached exhaust gasket once; although that made a noise that sounded like a mechanical knock from inside the car, rather than a gaseous noise. As you've changed the gaskets already though, it might be worth unwrapping the primaries to check they aren't cracked or anything before doing anything more drastic I'd have thought. Are your manifolds stainless? I've heard stories that mild steel manifolds rot badly when they are wrapped.

ChrisJC · Post by **ChrisJC** » Thu Dec 12, 2013 8:49 pm

Compression test. Unless the head gasket has gone at the ends, it won't interfere with the cooling system at all.

Chris.

DaviesDJ · Post by **DaviesDJ** » Thu Dec 12, 2013 9:07 pm

Think your right mate - as mentioned must do a compression test. Will check breathers, and unwrap primaries if the compression tests are all normal. Will post the results here tomorrow and would appreciate every bodies opinion. Thanks guys. If it indicates a leak then it's a top end rebuild, a pain in the arse but a chance to change a few things:-) got some ceramic coat I want to apply, back cut the valves etc. it's a composite gasket on skimmed surfaces that has never overheated and is only 5000 miles old- but it has had the occasional 100 shot of NOS put through it, but as I said it started on a standard drive into town. ARP bolts in situ obviously

mgbv8 · Post by **mgbv8** » Thu Dec 12, 2013 9:55 pm

Have a good look with a torch along the sides of the heads where they meet the block. Look for any signs of staining, especially around the sides of cylinders 4 and 6 ???

Dont get fooled into thinking that an ARP top end will stop head gaskets blowing ???

Do a compression test asap. You can blow the shite out of the sides of the head gaskets while not causing any other problems like over pressurising the cooling system. But you will hear the noise you have mentioned. And prolonged use with this type of failure can lead to damage to head or block faces.
I've blown loads this way on nitrous. And 99% of the time it was the drivers side for some reason ??

JSF55 · Post by **JSF55** » Thu Dec 12, 2013 10:35 pm

Here's mine found the hole in the rocker cover too small, so opened it up and it went away, same as a restricted flow

mgbv8 · Post by **mgbv8** » Thu Dec 12, 2013 10:58 pm

JSF55 wrote:Here's mine found the hole in the rocker cover too small, so opened it up and it went away, same as a restricted flow

If you have a half inch bore breather into the carb + the small K&N breather and it was squeeling through the small breather you must have a lot of blow by at idle or a blockage in the large breather?

Did you try removing the oil filler cap to see if it went away?

DaviesDJ · Post by **DaviesDJ** » Fri Dec 13, 2013 11:42 am

Done the pressure test and the results are as follows.

1 - 189psi 2- 200psi
3 - 202psi. 4 - 199psi
5 - 200psi. 5 - 103psi
7 - 197psi. 8 - 200psi

And the noise was preset when testing gues which cylinder!!??
No prize here for seeing where the problem is. As elizabeththe first once said...

Anyway thanks for those pics!! Funny how its always the drivers side!! Plugs are quite inconsistent despit consistent pressure readings in all but 6. Here is a pic of the plugs, and the car to put it uni context.

<a href="http://s1064.photobucket.com/user/davie ... 5.jpg.html" target="_blank"><img src="http://i1064.photobucket.com/albums/u36 ... mage-5.jpg" border="0" alt="Landy photo image-5.jpg"/></a>

<a href="http://s1064.photobucket.com/user/davie ... 6.jpg.html" target="_blank"><img src="http://i1064.photobucket.com/albums/u36 ... mage-6.jpg" border="0" alt="Plugs photo image-6.jpg"/></a>

DaviesDJ · Post by **DaviesDJ** » Fri Dec 13, 2013 12:37 pm

Those figures actually were with no throttle open during testing
- forgot

mgbv8 · Post by **mgbv8** » Fri Dec 13, 2013 12:41 pm

DaviesDJ wrote:Done the pressure test and the results are as follows.

1 - 189psi 2- 200psi
3 - 202psi. 4 - 199psi
5 - 200psi. 5 - 103psi
7 - 197psi. 8 - 200psi

And the noise was preset when testing gues which cylinder!!??
No prize here for seeing where the problem is. As elizabeththe first once said...

Anyway thanks for those pics!! Funny how its always the drivers side!! Plugs are quite inconsistent despit consistent pressure readings in all but 6. Here is a pic of the plugs, and the car to put it uni context.

<a href="http://s1064.photobucket.com/user/davie ... 5.jpg.html" target="_blank"><img src="http://i1064.photobucket.com/albums/u36 ... mage-5.jpg" border="0" alt="Landy photo image-5.jpg"/></a>

<a href="http://s1064.photobucket.com/user/davie ... 6.jpg.html" target="_blank"><img src="http://i1064.photobucket.com/albums/u36 ... mage-6.jpg" border="0" alt="Plugs photo image-6.jpg"/></a>

Is yours a left hand drive then ??

Quagmire · Post by **Quagmire** » Fri Dec 13, 2013 1:21 pm

I had head gasket failure once and it sounded like pinging - when I did the compression test I was getting almost a "crack-like" sound, pretty much the same as when you switch a very high current electrical load on.

sidecar · Post by **sidecar** » Fri Dec 13, 2013 1:39 pm

My engine started to make strange hissing sounds in time with one of the cylinders, it turned out to be a blown head gasket like the ones already posted up. Mine was not as bad as the pictures and there was no damage to the block, I think that I was lucky.

I put the failure down to a few things:-

1. Running too much NOS without retarding the ignition (I think that I was running around a 115 BHP shot on an engine which was not built from the ground up for NOS, the CR was up at 10:1)

2. The huge crappy chamfers that Rover put on the tops of the liners

3. The standard comp head gaskets which allow half of the firing ring to be 'floating about' and not be compressed between the block and the heads.

I looked into several fixes for this and in the end went for the following:-

Reduced the NOS shot to 100 BHP
Fitted an MSD ignition system that allows for a NOS retard, I went for 4 degree retard when the NOS is running.
I also sprayed each head gasket with a silicon copper spray and let it cure before fitting the gaskets and heads. (I run ARP head studs)

I toyed with O ringing the heads and getting copper gaskets made but apparentley they can have issues too.

I also checked out Cometic MLS head gaskets, they are expensive but they can have over size bores which at least puts the firing ring in the right place!

If you do have a head gasket issue I'd fix it ASAP otherwise you will burn and/or anneal the heads and block (cylinder 5 looks well low to me!)

I guess if you are running 5 litres under 'normal' Rover heads your peak cylinder pressure will be pretty high, the NOS could then push this into detonation and or head gasket failure.

DaviesDJ · Post by **DaviesDJ** » Fri Dec 13, 2013 3:31 pm

Sorry !! Sorry!! Got them arse backwards!! It's cylinder 5 that's leaking (low comp) on the drivers side! Only driven 7 miles since the noise started and will not be driven again. Heads of, new composite gasket and check the head is flat- if not the smallest skim possible. Am quite please with the numbers on he others. Will also program the megajolt to retard when on NOS. never formally tested, but with a TVr 500 cam what sort of numbers for the static compression do you think 200psi indicates???