Topic: chuffing V8 (Read 1608 times)

pas · « **on:** October 01, 2007, 20:58:35 »

hi Guys

does anyone know how I can tell whether I have a porous block on my 3.9 or just a blown head gasket/warped head, with out stripping the heads off, its blowing alot of steam/smoke out of the exhaust, using alot of water (no oil) and gurgling out the expansion tank when cold on idle (and out the saprk plug holes when the plugs are out.) the compression is a bit low as shown here

2)100 4) 90 6)90 8)95
1)100 3) 65 5)70 7)80

any ideas

cheers

Paul

Skibum346 · « **Reply #1 on:** October 02, 2007, 01:39:50 »

A garage can do a coolant test with a chemical indicator to see if there are exhaust gases in the coolant. Course... a negative result doesn't mean it's fine.... just means the break, if any, may be somewhere else!

disco-v8 · « **Reply #2 on:** October 02, 2007, 02:24:17 »

for one there is no thing as a porous block!!!!!! get that out your head straight away, as the side walls of a V8 block are very thin because of the sand casting when first made, they end up having a problem where one wall will be thicker one side and thin the other, so with the super crappy rover ECU set up they run super hot and make the crappy thin wall crack ever so slightly making the coolent push up past cylender liner..... this is a very common problem with 3.9/ 4.2/4.0/4.6 as they are all the same bore size.... dont usualy get this problem with the smaller bore on the 3.5....

doing a coolent snif test will not tell you anything, as exhaust gas will be getting into the coolent system either through the blown head gasket, or through the crack in the block.....

to my no how, the only way to find out is to take off the heads, and check the head gaskets, if they look ok and you cant see any blow through bits then, you might have the problem of a cracked block, if this is the case you would have to strip the hole lot down and get the block pressure tested.......

you might not even be thinking of doing this if the block is cracked, but top hat liners dont work!!!!! they just stop the coolent going up into the piston, but instead is forced down into the sump :o froffy oil!!!!!

i have not tryed this product out but i am willing to do so if the time comes, but there is a product from america that you can buy off Ebay that you stick in the coolent system which is ment to sort out all cracks in the block and i think its has ceramic in it so does a good job of stoping the leak, its abit like holts stop leak for radiators

IMO i would do the compression test again but see how long it takes to lose compression in each cylender, if its fast enough its most proberly the gasket as the pressure cant be lose very quickerly past the tiny cracks in the block, but when the engine is hot the water can steam past the cracks...... by the looks of it with the results you've given its most proberly head gasket, on pistons 1 3 5 7 as they all seem to be losing some compresion......

i realy dont no how the hell you've managed to get 10.0 bar on the standard 3.9 heads (itake it these result are in BARs) as the comprssion ratio is 9.35 so the most you should get is 9.3bar... to me you heads and pistons are very coked up and i bet the hole engine could do with a strip downand a good rebuild doing.....

in simple terms i recon its your right hand bank gasket (while looking at the engine from the front) so just change both gaskets, very cheap to buy them and make sure you buy new head bolts aswell as the later 10 bolt heads (3.9 version) had strtch bolts and CAN ONLY BE USED ONE!!!!!! you could go the more exspesive way like i have down and buy a tud kit for the heads so you can take them off loads of times and also not worry about stripping the thread in the block..

hope this has help you

Borky · « **Reply #3 on:** October 02, 2007, 08:07:21 »

there's a product called Holts Wonderweld thats supposed to seal cracks in blocks. Its quite a common product that you should be able to get at most motor factors etc, I've never used it myself but I've sold quite a few at work over the years.

burgerman · « **Reply #4 on:** October 02, 2007, 09:36:09 »

there is a process called ceramic sealing, this is done by a specialist, Very simply (which its not) you block off all waterways in the block apart from a in and out, then pump a hot ceramic solution through the casting for quite a period of time, in our experience it has always worked fine but blooming expensine !! we mainly used it on rare pre war riley and era blocks which were pretty much irreplaceable, i wuold suggest IF it is a block problem ( lets hope not) a replacement block would be MUCH cheaper than sealing, Anyhow good luck with things

pas · « **Reply #5 on:** October 02, 2007, 13:37:55 »

thanks for the replies guys

the readings are actually in PSI and so very low

yes its a 3.9 Block and have just spoken to a place that does head machining so they will have alook at the heads when I get them there

it get a bit complicated with my engine as its a 3.9 block with 3.5 heads that I gas flowed (they were skimmed a few years back) but with composite head gasket, I redid the rings about 6months ago so they should be ok, so as you can see I have no idea what the comp ratio will be. but I guess I'll find out tonight whats up when the heads come off.

cheers

Paul

pas · « **Reply #6 on:** October 07, 2007, 15:43:30 »

the saga continues (along with my run of bad luck) I stripped the engine and didn't find any obvious signs of leakage but took the heads to be checked out and consequently skimmed (they needed 0.014" skim) so hopefully now they will be ok

BUT when I started to refit them today I managed to strip one of the threads in the block

so now the question is can I helicoul the block and if so does anyone know what size the bolts are (as I don't have a guage)

cheers

Paul

Range Rover Blues · « **Reply #7 on:** October 09, 2007, 12:07:28 »

Yes you can helicoil the block, don't know what size the bolts are though.

The 3.5 EFi heads are the same as 3.9 heads anyway.

I'd agree from those figures that you have a problem with the 3,5 and 7. Is that the LH bank by any chance? just where it went on RRR after dumping the coolant. That side of the engine runs hotter on some cars due to the way it's installed.

You can guestimate the new C:R given the following.

Tin gaskets are 0.5mm when intstalled, composite are 1.2mm

on the front of the driver's side head (back of the other head) there is a pointless square protrusion with a hole in the end of it. On a new head this hole is equidistant from the hasket face and the side of the 'lug'. As the head is skimmed it moves closer to the gasket face. Obvioulsy it can't be totaly acurate as you are machining the head because it has warped, so often the C:R in the outer cylinders rises more because the heads go concave.

pas · « **Reply #8 on:** October 09, 2007, 18:42:10 »

cheers

i've now got a "Recoil" kit for this (its 7/16 UNC according to the rimmer brothers website for head bolts) just a pain that i've been able to get everything except a handle for the thread tap

Paul

BrumLee · « **Reply #9 on:** October 09, 2007, 18:56:41 »

Paul, if you've got multi-sided sockets, not hex, you'll find one of them will fit the tap.

Range Rover Blues · « **Reply #10 on:** October 11, 2007, 17:28:18 »

Shame you aren't closer as I have some.

pas · « **Reply #11 on:** October 11, 2007, 23:09:00 »

cheers guys

I found that I actually had a handle that, with a little modification, fitted. I was suprised how easy it is to do, so much so that next time I have to take the heads off I may consider doing the lot as its a much better thread now, but hopefully that won't be for some time. I have to admit I was a bit nervous about drilling out the thread , as it was a 11.5mm drill bit that would only fit into my 240v drill (that doesn't go very slow) so there was ali flying everywhere whilst I prayed I was drilling straight

, but the heads back on now , just got to put the rest back on and hopefully it will be play time again soon :twisted:

Paul

Range Rover Blues · « **Reply #12 on:** October 13, 2007, 19:05:07 »

TBH I'd only do them as and when needed, take as little metal off the block as you have to. A set of studs might be a better bet to protect the threads that are left.

pas · « **Reply #13 on:** October 14, 2007, 15:48:55 »

well

i'm back to being p***ed off again now as i've got the engine back tigether and running but have still got a gurgling expansion bottle
so just got to figure out what next

Paul

Range Rover Blues · « **Reply #14 on:** October 16, 2007, 01:04:23 »

Oh nuts.

You need a leakdown tester and samll compressor then to find out which one and how bad.

Could be a cracked head or cracked block, the miss-named porous block syndrome.

Most likely head though if it's bubbling, find out which one and rebuild or replace it.

You could try disconnecting the leads & removing the plugs one at a time and see if it stops bubling I guess, that would tell you which one.

pas · « **Reply #15 on:** October 16, 2007, 19:00:45 »

i think its on number 7 as that spark plug was "washed" in comparison to the others last time and this time it was wet (with water) so my last attempt (as when the heads were skimmed they said the heads were good) to sort it is iv'e ordered some "CarGo Seal up" that I think someone recommended to me in the past as being good stuff. so this is it if it doesn't sort it i goes its new engine time

will let you know if it works

Range Rover Blues · « **Reply #16 on:** October 17, 2007, 01:25:10 »

I think it's cargo seal my mate sells as a heavy duty repair, do you have to drop all the antifreeze to do it?

He sells a 2 part fix with a bottle of K-Seal to fit and forget once you've done the first treatment. It does work.

disco-v8 · « **Reply #17 on:** October 17, 2007, 01:56:43 »

this cargo seal up....

on the instructions its says:-

empty radiator system
fill up with fresh water
run engine till hot and all valves are open
add seal up
run untill leak stops??????????????????????????????
empty cooling system and flush out all seal-up
leave for 3 hours to set
fill with water and anti freeze

well if youve got a cracked block like alot of rover V8's how are you ment to know when the crack is filled and when to flush the cargo seal-up out????

or do you just risk it and leave it in to make sure, and flush it out and let it set after a day or two?????

Range Rover Blues · « **Reply #18 on:** October 17, 2007, 02:11:18 »

I guess you keep running it untill it doesn't misfire from the wet plug and doesn't steam anymore.

Improtantly though the stuff I'm familiar with will set if it comes into contact with antifreeze, so you need to flush very thoroughly ie twice. You can leave it for more than 3 hours too. Perhaps drive it around for an hour then let it cool down, once cool then drop the water and leave it overnight.

pas · « **Reply #19 on:** October 17, 2007, 10:32:19 »

shouldnt be any problem with antifreeze as the amount of water i've hd to put in it recently (probably over 20l) and the fact that i NEVER put antifreeze in staight after a rebuild after having to drop the water again too many times (gets a bit expensive :twisted: ) but yes its that stuff,

i think with mine it would be obvious in that the water will stop gurgling out of the expansion bottle (was going to put a vid clip attachment but it doesn't recognise the file extension) ah well I guess we'll see when i get back from my hols

cheers

Paul

Range Rover Blues · « **Reply #20 on:** October 18, 2007, 00:33:28 »

If it's gurgling in the tank then perhaps remove the plug from the offending cylinder to allow the water pressure to get the stuff into the crack, definitely leave it under pressure as it cools too.

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AuthorTopic: chuffing V8 (Read 1608 times)