Daemon4x4 - 4x4 & Off Road Technical Board

Daemon4x4 - 4x4 & Off Road Technical Board

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#129-02-2012 12:20:38

Oil leak....

mine has resurfaced after 2 years from putting on a new head gasket.
It leaks from between the head and the block at the rear, runs down the bell housing and then by magic spreads
everywhere before finding the lowest point and dripping.

My theory is that the oil feed to the head is at the back on the outer edge of the head. With a new 5 hole head
gasket the seal rings around the pots are quite thick and you tighten them down and they crush, but the rest of the gasket
has just got raised rims around he various holes for water and the single oil feed at the rear.
The only thing i can think is that the oil pressure through the gasket is high at that point and the combination of the thicker
5 hole head gasket has reduced the sealing around the oil feed to the head and over time it has managed to squeeze past the
raised rims, and once a flow starts it just gets bigger.
Now wether the head was dinked when putting it back on at the outer edge near the oil feed hole, or the head needs skimming
due to its bad installation first time round before i owned the truck i don't know all i know is its gunna cost me money to fix......

What would the ramifications be of giving the head bolts an 1/8th of a turn to try and nip the bugger down prior to major head surgery/wallet raping ?

#229-02-2012 14:35:13

Re: Oil leak....

Icon - Post link Paul1566 wrote:

What would the ramifications be of giving the head bolts an 1/8th of a turn to try and nip the bugger down prior to major head surgery/wallet raping ?
Potentially disasterous. I wouldn't. The bolts are done up to a set position, you could easily over-stretch them and it'll result in actually the opposite of what you're trying to achieve.

The head gasket is steel shim, regardless of its thickness, there is very little to 'crush' thats why head and block face need to be exactly flat. It won't take up any voids or gaps like a normal gasket, and why its so easy to bugger up the job if you arn't really careful lowering the head and seating gasket when doing it.

If you sure its coming from between the head gasket, best bet is to remove head and measure the block deck for straightness. Stevo used to get me a composite type gasket for any blocks that were slightly suspect. (well once or twice anyway, but we had no trouble with it after.) Its not ideal as they can't take the same compression pressure like a steel shim one but it worked for me.

Are you sure its not coming from the turbo oil feed banjo bolt? Its just below the level of the head gasket at the back on the drivers side, it can pee oil all over the bellhousing.

#329-02-2012 15:11:06

Re: Oil leak....

TonyN, i don't think its the banjo bolt, had me mirror on a stick out and after a good clean i can see it starts to run down from just under the gasket and pool in the middle top of the bell housing before finding its way downwards.
Banjo bolts round to the side is it not ?
Didn't mean crush the head gasket as such, just the soft black covering like stuff thats all over bar the top of the pots.
As you say best to pull it off and check block and head for levelness.
Bolts where replaced last head change, would they need changing again ?

#429-02-2012 15:52:54

Re: Oil leak....

Icon - Post link Paul1566 wrote:

As you say best to pull it off and check block and head for levelness.
A couple of simple ways of checking the head and block are to either use engineers blue smeared on one surface, else a verified straight edge. The metal carriage rod out of a printer is a cheap option. The one which the print carriage runs on. They're nigh on perfect straightness.

Bolts where replaced last head change, would they need changing again ?
Yup. One shot bolts.

#529-02-2012 15:55:07

Re: Oil leak....

"Yup. One shot bolts."

bugger thats more expense and a stupid idea.......

#629-02-2012 16:24:06

Re: Oil leak....

Even if they were intended to be reused, would you honestly trust a used long bolt in such a critical application?

#729-02-2012 16:28:37

Re: Oil leak....

Studs get reused on engines, why not bolts ?

Or is it that studs would only be on an ali to ali combination and not steel to ali ?

Saying that i am sure my old isuzu had ali head with cast block and that had studs...... brain hurts now.....

#801-03-2012 08:38:53

Re: Oil leak....

Just read the manual and it does not refer to replacing the bolts every time.....
Just inspect and discard any that are broken or deformed.....

#901-03-2012 11:40:43

Re: Oil leak....

They are so cheap why risk it? The sole purpose of the bolts is to hold the head down under tension, everytime you stretch them and then undo them you'll weaken them.

The manual says measure them at a specific section and if they've over stretched they will be thinner than a set measurement.

A lot of the aftermarket bolts don't have the thinner section to check them, I doubt who ever did your head used genuine bolts.

Why go through all this and then risk it on £30s worth of head bolts?

Stretch bolts are a better idea than old tech bolts as they never need retightening, they can't loosen like a normal nut and bolt, fit them right and you can forget about them.

big_smile

#1001-03-2012 12:05:03

Re: Oil leak....

Not saying I won't change them, just wondered if the manual (downloaded from here) don't say change them how many haven't and suffered ?

Anyway they should have made them bigger so they don't stretch keeping all the pixies working harder inside and stop the oil escaping..... tongue

The last head gasket change was done by me, the bolts where roughtrax ones, and i was pretty careful when re assembling the thing cus
the reason i changed it was the same oil leak, and spending all that money to stop a drip was hurting......

It held out for 2 yearsish, but obviously the culprit was not the original gasket but something else. This time i will check and check again.......

I'm learning slowly.....  big_smile
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