Engine top end

[Falcon_LS]

I'm going to be sorting out my worn valve guide/seals problem this June (Mitsubishi 3.0L), and I've decided to take things slow. To save time, I'm going to buy a used cylinder head, so once it's ready it's only a matter of swapping out the old one for this one. Don't think that should take more than half a day.

I plan on getting the "new" head machined, and replacing the valve guides and seals on it with new OEM ones. But I was also wondering what else I should replace in the process. So far my list consists of:

- Head gasket
- Timing belt
- Valve cover gasket

You've obviously got the new coolant, etc. but is there anything else I should consider whilst the cylinder head is off the block? Thanks!

 

[demarpaint]

Make sure they mill the "new" head so it mates up perfectly to your engine.

Now there is a possibility that if the bottom end of your engine is worn, (rings, etc). It is possible you will start burning oil, and have lower end related engine problems. This can happen because now everything up top is nice and tight, and the bottom end has the wear typically associated with the miles on the engine. It doesn't happen all the time, but it can and does happen when re-doing heads.

Many years ago I swapped heads on a few Fords, and a Chevy 250 I6. I'd say out of maybe 4 engines that I did the head swap I had oil burning problems with one of them. It was a friends Maverick which was neglected to begin with.

 

[Johnny]

Add intake and exhaust gaskets to that list.

 

[Silk]

You need to replace the water pump on these engines too - they tend to seize,and then break the belt.Plus tensioner,idler,crank seal and auto tensioner.You only want to do it once.

 

[Falcon_LS]

Thanks for the responses!

Silk, I replace the water pump every second timing belt change. It was replaced in summer '08, do you reckon it's worth replacing? It has about 50k km on it now. Also, does the 12-valve version of this engine come with an auto tensioner?

Johnny - thanks, I've added those to the list!

Demarpaint, hopefully I will be lucky. I've treated the engine with ARX 3 times already, so I'm hoping that will be a positive.

 

[demarpaint]

Sounds like you took care of it, I'm thinking you'll be OK. Good luck and keep us informed!

 

[Falcon_LS]

Thanks very much, will do!

 

[StevieC]

The rings in these engines generally are good forever, it's usually the valve seals / guides that go 99.9% of the time.

I think with a properly machined/rebuilt head you should see another 250+ KM

I love these engines... They run smooth and keep going forever with minimal work. (I think your water pump is in good enough shape to last you until the timing belt you are putting on goes 100K)

Can we see pictures of the engine torn apart?

 

[mechtech2]

Uh... Isn't that engine a v6 with 2 heads?

 

[Falcon_LS]

Yes it is...and to clarify I will be buying a set, not just one side.

Steve, you're spot on. It's a bulletproof engine but the seals/guides are a PITA. Had the dealer replaced the guides instead of just the seals, I wouldn't have to be doing this right now...but I know it'll be done right. I'll definitely snap some pictures.

 

[c3po]

Originally Posted By: Falcon_LS
Yes it is...and to clarify I will be buying a set, not just one side.

Steve, you're spot on. It's a bulletproof engine but the seals/guides are a PITA. Had the dealer replaced the guides instead of just the seals, I wouldn't have to be doing this right now...but I know it'll be done right. I'll definitely snap some pictures.

I hope this is something that you will not have to do again in another 150,000 miles or so.

 

[Falcon_LS]

Originally Posted By: c3po
I hope this is something that you will not have to do again in another 150,000 miles or so.


I hope so! So far this vehicle's been good to me, so I don't mind spending on the old girl. Should keep her on the road for a good couple of years.

 

[StevieC]

Money well spent on this engine IMO, especially because you know the service history of it and the reliability track record of these bottom ends is superb!

You will be

all the way to the bank after the repair for quite a while.

After you put the new heads on I would run a half a bottle of ARX in the oil to well soak the new valve seals and new rocker cover gaskets etc. and start them off nice and pliable. Just a thought.

 

[Falcon_LS]

That's exactly one of the reasons why I'm dead set on keeping this truck for as long as I possibly can, Steve. That and their spares are cheaper compared to the newer engines. The only place that's buying this vehicle is the junk yard and that's a long time away.

Half a bottle of ARX is a very good idea...I was considering a treatment, followed by the maintenance dose, but that sounds like a much better idea. Especially since I'm considering 20,000 km/1 year OCI's after this on a full synthetic (with a UOA of course).

 

[StevieC]

Sounds good!

 

[Silk]

Originally Posted By: Falcon_LS
I replace the water pump every second timing belt change. It was replaced in summer '08, do you reckon it's worth replacing? It has about 50k km on it now. Also, does the 12-valve version of this engine come with an auto tensioner?


They don't often go past 200,000km,but if it's only done 50,000 I wouldn't worry,same with the tensioners.Do the seal though,more than 200,000km is pushing it.We have never done guides,it's just the valve guide seals that need replacing.Dunno about the auto tensioner,I thought they did,but will check tomorrow.

 

[Falcon_LS]

Cheers, Silk. Would muchly appreciate it. The tensioner assembly part number is MD104578, if it helps.

 

[Falcon_LS]

This is definitely going to be good fun. Done the timing belt before, but this looks like even more fun:

Will have to dig out some more exploded diagrams to transfer the distributor across. Would it be alright to coat the new seals with synthetic oil and a touch of ARX?

 

[tom slick]

You haven't mentioned replacing the valves or the seats being cut, I'd hope you are also getting that done.

 

[Falcon_LS]

Tom, I'm getting the valves lapped if that is what you're referring to?