Volvo Penta 2002 engine rebuild completed with a final question or two for the forum experts

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petergarth

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'With a little help from my friends' I have successfully rebuilt my Volvo 2002 circa 1988.
It's back in the boat and I'm busy running it in.

I've been advised to re torque the head bolts after 10 hrs. and then re set the valve clearances.
I thought I'd do a little research on this and there seems to be a lot of 'discussion' out there.

On the question of 'hot or cold' it seems the majority of the comments lean towards doing this with the engine cold ???

On the question of 'should it be done or not' many comments suggest this is now no longer necessary with modern head gasket materials.
So, old school advice is...'old school'? Is this true?

I bought my parts from a site in the UK called Parts4engines and I have asked them for advice on whether the gasket they supplied falls into the category of 'does not need to be re torqued or not'.
Waiting for an answer. But in all fairness I'm not sure they are really qualified to advise me on this.

Does anyone on the forum have any experience or possibly any information from Volvo on this??
Look forward to the comments of the forum experts.

Many thanks
 
The workshop manual doesn't mention any need to re-torque the cylinder head bolts, just to torque them to 70Nm.

The workshop manual says setting the 0.30mm valve clearance should be done with a cold/warm engine.
 
pvb said:
The workshop manual doesn't mention any need to re-torque the cylinder head bolts, just to torque them to 70Nm.

The workshop manual says setting the 0.30mm valve clearance should be done with a cold/warm engine.
Click to expand...
You're quite right; it doesn't. For some reason, I thought it did and just checked! But I retorqued mine after some hours running, along with checking the valve clearances, and a) the bolts took up a little and b) it ran better afterwards!
 
I did torque the head down, in two stages if I remember correctly, last one to 70Nm, as per the manual and in the bolt sequence set out.
Set the valves at 0.3mm cold.

All good so far and running nicely.
I did not see anything in the manual either but happy to hear you confirm I need not do it.

The idea 'breaking' the bolt 'seals' that seem to be working now, to tighten them doesn't seem logical. Specially when you now get you apparently get head bolts that are designed to be tightened just once.
I did use new bolts but once again I'm not sure if they are these 'once use' bolts or not.
I'd not heard about them until a few minutes ago.

But I take the point that older generation gaskets may settle a bit and need nipping up.

As in boat ownership maintenance it's always a case of more questions than answers :)
Thanks for the response.
 
With these conflicting opinions you see why I'm concerned.
Why not do it?
Well it's not a difficult thing to do but these are some of the comments I've had here and elsewhere:
1. breaking that new original bolt seal is not a good thing
2. when you re tighten it will not be accurate and may over tighten
3. you may have used these 'tighten once only' bolts and should remove them and replace with a new set.
4. any bolts should only be used once so if you want to nip down the gasket, use new bolts :(

You can see where these are going..........
and why I am wanting to be convinced to leave well alone ( as per the manual apparently)
 
I think re-torquing was maybe standard in olden times. The manual for the old MD1 B engine says to torque the head, then run the engine until it's warm, then re-torque.
 
pvb said:
I think re-torquing was maybe standard in olden times. The manual for the old MD1 B engine says to torque the head, then run the engine until it's warm, then re-torque.
Click to expand...
And, while I checked and it isn't in the Workshop Manual, I certainly read somewhere that the cylinder head bolts on a 2003 should be retorqued after a few hours running , but I can't recall where! I wouldn't have done it without good reason; I'm a great believer in "if it ain't broke, don't fix it!"
 
I've never re-torqued the head bolts on the engines I've rebuilt although I do re-check the valve clearances once the engine has bedded in.

I don't think that there is any downside with checking the head bolts but I've never needed to.

Richard
 
Very unlikely that the new bolts are stretch bolts on an old engine design. I'm an old fashioned mechanic and still retorque.

But then I also reuse stretch bolts and have never had a problem doing so.

I also grease all threads that are to be torqued, habit of a lifetime.
 
Thanks for all the advise for and against. I’ve also in the meantime had a chat t the engineering shop who honed the bores and resurface the valve seals.
He recommends I re torque. One bolt at a time. Slack off then re tighten to 70Nm. And because the motor is a pushrod unit to reset valves.
Also and I’ve not seen this anywhere he recommends using a mono grade WD 40 oil during the run in period. Sadly I’ve used my regular 15W40 but will change it tomorrow before running any further. And to use this oil until it changes color or for at least another 10hours of use. Oh yes I did use MD grease on the bolts as per the manual.
So I’m going ahead as per the advise. As someone said, why not, it’s no big deal. Thanks again to all
 
Hi Richard
That's the problem. Everyone is trying to help, giving their opinions, based on their experience.
It's all well intentioned so who's advise does one accept as being correct.
The engineering shop guy is dealing with these issues on a daily basis, over years. I am doing this once in a lifetime (hopefully).
I feel his opinion should carry some weight.
Another guy who has spent his working life on diesels here locally and has a boat with a Volvo coincidently, says to set the torque wrench just a few Nm higher so as to ensure the tightening process is actually working. He says if you use the 70Nm setting on the wrench it will not actually have any benefit. I suppose because we are dealing with very small tolerances in nipping up the bolts.
So here is another example of an opinion based on years of personal experience.
Who do I believe?
My feeling is that the idea of setting the wrench just a little higher sounds better than loosening the bolt slightly.
But who wnows :(
 
petergarth said:
Hi Richard
That's the problem. Everyone is trying to help, giving their opinions, based on their experience.
It's all well intentioned so who's advise does one accept as being correct.
The engineering shop guy is dealing with these issues on a daily basis, over years. I am doing this once in a lifetime (hopefully).
I feel his opinion should carry some weight.
Another guy who has spent his working life on diesels here locally and has a boat with a Volvo coincidently, says to set the torque wrench just a few Nm higher so as to ensure the tightening process is actually working. He says if you use the 70Nm setting on the wrench it will not actually have any benefit. I suppose because we are dealing with very small tolerances in nipping up the bolts.
So here is another example of an opinion based on years of personal experience.
Who do I believe?
My feeling is that the idea of setting the wrench just a little higher sounds better than loosening the bolt slightly.
But who wnows :(
Click to expand...
I tighten the bolts progressively in, say 15 Nm stages, in the sequence specified (usually inside to outside diagonally) so you should get a good idea as to whether everything is nipping up properly. Certainly there's no harm in going 5 Nm higher than spec. It's the tiniest nudge on the wrench at these torques.

I can't see any advantage in loosening and then tightening but I can see disadvantages.

Richard
 
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