port and polishing

[VL Berlina 5speed]

Basically as i've told ucwepn before the rb30 mainly crack in the cam tunnel on the exhaust side and the crack's only going to get longer and make it harder to weld if it cracked you then need the cam tunnel rebored so the cam can move nice and free again. They also sometimes corrode through the water galleries and leak into the exhaust ports. The only difference between NA and turbo is cam we've compared the heads at work and there's no difference in ports vavles or similar things. The only way i could see heat difference is the turbo produces more heat therefore heating it more evenly. Pressure testing is when the water jacklets are sealed with a plate and compression is pumped into the water galleries it's then emersed into well basically water and bubbles will come out where a leak is. There is also vacumn testing where air is sucked out and if it holds a stables pressure normally would indicate no leaks. Pressure is far more accurute. Your top price sounds good pressure testing sounds pricey but worth it (peice of piss takes 5 mins). Chemical welding never heard of but its sounds risky. I'd say it might be quick fix but won't last long.

so there is no set way of telling if it is the head or the gasket with out dismaterlig it, and yah i read waht you have said in the other thread started by ucwepn and that was helpful info:thumbsup:

 

[Pub247]

there is ways like water bubbles in radiator when engines running, Milky oil excessive steam from exhaust using lots of coolant overheating the basic ways. Oh sorry read your post better there ways but i'm no expert in engine diagnoses i just fix heads. But my opinion For example milky oil would to me indicate a cracked head as the crack would leak water into the the cam area where the oil is present. Bubbles would to me be a blown gasket as air be leaking into water galleries. Excessive steam could be either as water could be leaking into chambers or corroded through to ports. What sort of problems are you having?

 

[Pub247]

You could still do a pressure test with the head still together but is not ideal. Vac test would be alright but then its not 100%

 

[VL Berlina 5speed]

well i found a little bit of milky stuff undert the cap, stuck my finger in the rocker cover and couldnt fell any cream stuff or anything on my finger,
havnt notacied any steam coming out of the zorst, except the usal coldness in the morning,
ill check the bubbles in the radiator in the morning
the coolant was full when i got my car runnign fine and i notacied on saturday it was low at miniunum, so over two weeks it had dissepreard, so i think it is only a small crack or possibley a small brake in the gasket

couple weeks back i had some problems with missfirng and the CAS, i read on think it was calais turbo that the missfirng caused by stuffed head can cause the block to twist slightly and when you come to fit a new head it wont seal properly and jsut happen again, do you reackon the CAS/missfing could of had enough force to twist the head slightly causing the gasket to leak??

 

[Pub247]

I think a blown head gasket will notice pretty quickly and tend to be almost instant overheat and lots of coolant in exhaust (if its exhaust side) My guess is you won't find bubbles but look anyway. I think you have to have some pretty high revs and under heavy load to cause the head to twist like if it misfiring at idle it wouldn't be the cause. Overheating will warp the head quicker. They're pretty strong qaulity alloy and really prone to softness but are very common at cracking. Out of batch of 20 we get at least half of them cracked (magna's are worse though almost all). Have you checked all other places for leaks like hoses, pumps heater welsch plugs radiator?

 

[Pub247]

Basically with what you descibe it might be a small crack with the milky build up you decribe it might be worth changing the oil and see if its all milky.

 

[VL Berlina 5speed]

ive looked over the piping and radiator, but ill check the welch plugs as well tommorow
just remberd i repaired a leak in my radiator about a year ago with alrolddite, ill give taht a look at and see if i can see it shooting water anywere when its hot
the car missfires slightly, but the rev guage dosnt bounce at all but if u stand behind the car you can hear it,
ill b back with more info tommorow, cheers for your help 2day Pub:bow:

 

[Pub247]

No worries

 

[VL Berlina 5speed]

Basically with what you descibe it might be a small crack with the milky build up you decribe it might be worth changing the oil and see if its all milky.

pulld the dip stick out and its fine no liquard on it or creamy colour, and also i stuck my finger un side teh rocker cover and didnt find any of the creamy residue,
dosent the cream take a week or so to apper? as it could be that my car might of picked up mostire while it was sat round for a week and half, was a wet week if i recall correct

 

[Pub247]

Yeah ive seen it before on 202's but if your oil looks ok then maybe it's not but hard to tell without looking at it. But i'm no mechanic or expert but i can fix cracked heads and do pressure testing straightning that sort of ****.