ALH, how much boost on stock head bolts?

[Seatman]

Head gasket has started to seep a bit of pressure into the cooling system so I'm going to change it, currently at about 21.5psi max boost but will maybe be going to about 24-25psi max. Just wondering if I'll need different head bolts or not.

Cheers

 

[red16vdub]

from what i've read, OEM head bolts are good till around 26-27psi

 

[Seatman]

Sounds good, cheers

 

[Seatman]

Actual (I think), it's the GT1749VA in there just now but will be getting replaced with the VB unit.

 

[rotarykid]

Are you talking total boost, atmo+boost?? Or actual boost above atmo??

You do realize that with weather fronts and changes in elevation change static to a moving number, don't you?

Where I am from in the Carolina's static is a number that ranges from 13.9-14.5 PSI Lb gauge.

But up in the mountain west that number is 11.2-12.5 PSI Lb gauge.

The ECU takes a measurement of Atmo then allows a certain amount above that static measurement. So once you figure that in a stock head can handle another 18-22 PSI lb gauge above static without the gasket loosing cohesion.

But you can loose a head gasket with less if your engine temps get too high while under load......

 

[kiwibru]

I would worry about the rods going before a bad blown out H.G. Just add the insurance by mounting it back with ARP studs, then pray for your rods to hold on. The next weak point in the chain of rotational parts is !?

 

[poisas]

I have a friend with afn engine, .280 dss nozles bv50 turbo dbilas cam, 12mm pump, he is crazy and runs 2.5bar constant boost peaking at 3bar plus atmosferic pressure. Stock internals and stock head bolts he is taking part in locla slalom and rally competition, car is over 10000km with this setup the car is 4x4, he broke torsen 3 times, 2 times clutch failed, power is arount 150kw. And torque is around 500nm he can wheelspin in second gear straight, and 3rd gear in the corner. And he says that bolts is no issue at all. What he told thats important to have double valve springs so under high boost valves would not hang.

 

[mk1-83]

old head gaskets that sit as long as the block is old don't leak soon.
most headgasket problems is after head replacement to do warp head are bad intstall.

 

[Seatman]

old head gaskets that sit as long as the block is old don't leak soon.
most headgasket problems is after head replacement to do warp head are bad intstall.

Original head gasket at about 170,000 miles, to much pressure in the cooling system so it must be leaking a bit. Head certainly isn't warped, been there and seen that, car runs sweet and doesn't over heat, just the pressure build up. Pump pumps, coolant circulates, new genuine vw t stat recently too.

Worst was a honda, girl drove it till it gave up, head like a banana lol



Rotary kid, I'm talking about max boost in terms of 21.5 give or take allowing for weather and hill climbing lol



And death to the conrods, at least that's a bit more dramatic than a slightly leaking HG

 

[Bczuk]

Our daily driver runs 26 psi max on stock head bolts. Have around 15,000km on it so far after the upgrades and it has around 300,000km total. I don't hesitate to use the boost but don't beat on it hard every day or anything like that


If I ever take the head off I'd add ARP studs while in there

 

[VeeDubTDI]

Peak cylinder pressure is the big thing, which is caused by boost and injection timing. You're just as likely (or more so) to compromise the head gasket with too much boost as you are with timing that is too advanced. Combine the two together and it's double the fun.

 

[Seatman]

Mmmm interesting point, could be timing as I think it's fairly advanced. Got the head off now and going to upload pics in a bit. Looking for advice but I'll stick that in a new thread.

 

[mk1-83]

Also measure the piston height s so you can tell if there is a bent rod.

 

[Markus L]

Also measure the piston height s so you can tell if there is a bent rod.

You can hear a bent rod: Engine runs rough with light load in some rev range.

Head gasket can start leaking even in a stock engine if turbo vanes are sticking and rise EMP sky high.

 

[Yblocker]

If it's apart i'd go with the ARP studs. If you plan to keep the car, one advantage is that they are re-useable.

 

[IndigoBlueWagon]

Three things cause head gasket failure: boost, timing, and fuel. I managed to run 265K with a factory setup before swapping out the head. Used OE (not aftermarket) head bolts torqued to tighter than stock specs, which has worked for a lot of people. It didn't for me. I was running 26 PSI, PP520s, RC6. Not a ton of fuel, but a fair amount of boost and lots of timing.

I ended up with ARP head studs. If I had to do it again I'd go with studs. Cheaper than pulling, planing the head, and putting it back together.

And in my experience you can't always hear a bent rod. I bet some of yours are.

 

[Big Swole]

Studs = Insurance!

Been down this road with my very high hp diesel trucks.


No clue what my 02 is pushing for boost or drive pressures but I've had no issues since my mods... Hope I don't.

 

[Seatman]

IBW I thought we covered this already, you were running something like 200 at the wheels and screaming your tdi round a race track, hardly comparable to my situation lol.

I'm a 100% confident the rods are perfect.

 

[IndigoBlueWagon]

Let us know what you see when you pull the head.

 

[Seatman]

Let us know what you see when you pull the head.

Took it off last night bud and now I've been out to clean things up, it all looks perfect.

Never had any water in the bores, it was just pressuring the coolant and blowing it out around the fan switch lol. No idea how but that was it. No overheating or any other issues. Car ran mint other than the cooling system pressure.

 

[Seatman]

Meant to post this too, I started a new thread on the HG

http://forums.tdiclub.com/showthread.php?p=4751550#post4751550

 

[Curious Chris]

On my 2002 the head gasket went after I was running 26 psi boost sustained. It showed up as a coolant leak that I chased for 2 years. Yes I put in ARP studs when I changed the head gasket and since I was at 250,000 miles I changed the cam too.

 

[Seatman]

I ended up just using the stock bolts for now, buying another engine in the next couple of weeks and I can do any mods to it instead. Switched my mapping off as well for now to give the engine a chance and for me to make sure everything is tickety boo.

 

[terrydtdi]

I was pushing coolant out of the reservoir on high boost with my mods. When I changed my head out found no issues with the head. When I installed a fresh head with a port job and valve job definitely went with the ARP studs.

 

[BlankThis]

You were blowing coolant with a 15?

 

[terrydtdi]

I sure was, with boost spikes to 25 lbs.

Believe it or not this is the original turbo. I've had this tune since 140,000 miles. I'm finally going to be upgrading to a 17/22, pp764's and other goodies within a few weeks. So I'm sure rods will be in my near future as well.

 

[Seatman]

I think your HG was just old like mine and had become weak.

 

[rotarykid]

my guess it was boost and timing that lifted the head loose, I speak from many years of playing with timing, too early means you will be replacing the gasket in short order!

 

[poisas]

Speaking about advanced timing, I have advanced in vag com its in the middle between top and midle line. So its within spec. How much advanced is advanced to affect the head?

 

[VeeDubTDI]

Speaking about advanced timing, I have advanced in vag com its in the middle between top and midle line. So its within spec. How much advanced is advanced to affect the head?

I suppose that depends on how much power you're producing. The more power, the less advanced you can run it. Remember, it's about peak cylinder pressures, which are a combination of boost, fuel, and timing.

As for how much is too much, I can't actually quantify that.