I bought a 2008 Volvo XC70 off of Facebook Marketplace. I came across it while scrolling as I often do, and this caught my eye and I just fell in love with it. I love the way it looks. The price was also quite attractive, however, the reason for that was that it had some damage to the engine. After doing a bit of research on the engines these have and what the likely issue was, I decided to take a gamble on it and try fixing it. Here's how I did it.
This is just after I picked it up.
And this is after I got it home. The Land Rover towed it just fine.
I discovered it had an aftermarket trailer brake controller installed in it, which I didn't intend to use at all so I removed it. However in the process of removing it I found that the brake switch wire was fuse tapped straight into the fuse panel. This means that the brake controller 'thinks' the brake pedal is pressed all the time, because the wire is on ignition power instead of brake lights. So I don't see how the trailer brake controller could have ever worked, but it doesn't really matter to me since I'm taking it out anyway.
Starting to take the top of the engine apart. After taking the top cover off it was immediately clear to me what the problem was and it was exactly what I suspected. The timing belt has jumped some teeth so the valve timing was out of sync with the pistons. This has caused the pistons to impact the valves (but only the intake valves) and the weakest link in the chain has broken.
In this picture you can just about see some of the damage. Directly under each cam lobe there is a half circle of aluminium cast into the head, this should be a full circle, the aluminium of the casting has actually broken.
Camshafts out, and the damage is becoming more visible.
Head off the engine and on the bench. I spent some time disassembling and cleaning the head, which I did by putting it in the dishwasher a few times which actually worked amazingly well to clean all the carbon away.
This is one bit I was a little worried about, because valves have touched pistons it's entirely possible that the pistons or cylinder bored could be damaged. However I got extremely lucky and there is not even a mark on the pistons. Everything on the bottom end seems fine.
Here you can see a bit more clearly what's broken. There are holes drilled into a protruding part of the casting which leaves a relatively thin wall next to the holes, and that is where they've broken. This is not necessarily a bad thing because they act a bit like a fuse, they fail so that other harder to fix things don't.
These holes are for the automatic valve lash adjusters, sometimes called tappets or lifters. They have a pressurised oil supply and an oil drain at the bottom. Here I've started to grind the broken area back a bit with a die grinder.
All ground back to fresh metal. In this picture you can see what the lash adjuster holes are supposed to look like. All the ones on the exhaust side (closer to camera) are still intact.
Here I've built up the broken area with weld. This new material is what will get machined to make the new holes out of.
Here I'm 'machining' the weld material to a flat surface. I say machining in inverted commas because I'm only using a drill press, albeit a fairly good one, and a modified old broken drill bit that I reground to be a bit like an end-mill.
This is the resulting flat machined surface, it's not very pretty or smooth, but that's okay because it doesn't need to be. This is just to mark out and drill a hole in the right place, it's not a precise surface.
I got a drill bit and a 12mm reamer to make the holes for the lash adjusters more precisely and to give the inside of the holes a much smoother surface finish. Regular twist drill bits actually leave a very rough surface on the inside of the hole they drill, and these surfaces need to hold oil pressure so a reamer was needed as well.
This is the first hole drilled and reamed, it came out quite well. This shows well the oil supply port at the back of the lash adjuster hole which is made by a cross drilling that goes through almost the whole length of the head.
The lash adjuster fits nicely in the bore.
I then proceeded to do the same welding and machining on the other 9 broken areas.
Drilling the rest of the holes. It took a lot of careful measurement and marking out to get the holes in the right spot.
Another very important tool, which I actually had to fabricate myself, was a very super extra long 8mm drill bit to clear out the cross drilling that supplies oil to the lash adjusters. This drilling would of course have got filled up a bit by weld in places, so it needed to be re drilled.
This is the oil cross drilling hole after I ran the long drill bit through it to clear out any weld material out from inside.
Drilling an oil drain hole at the bottom of the lifter bore to make sure oil doesn't pressurise the lifter from underneath.
Finely adjusting the height of the surface each lifter sits on to make sure they all sit at the right height.
The cross drilling hole welded back up and sealed on the outside after cleaning the internal oil passages.
Cleaning up the bottom head surface using my favourite method, sandpaper stuck down to a sheet of glass. I also lapped the valves back into their seats to ensure a good seal.
Cleaning up the top surface of the head where the valve cover and cam covers sit.
New valve stem seals installed. The old ones didn't seem bad but it's worth doing while the head's off.
Valves and springs reinstalled in the head.
The engine block deck cleaned of any old gasket material so the new head gasket can seal nicely.
New head gasket installed and alignment dowels inserted ready for the head to go on.
Cylinder head with rocker arms already in placed back onto the engine block.
New head bolts dropped in and lubricated ready to be tightened down.
Head bolts torqued to spec using a torque wrench and an angle gauge with markings to track each stage.
Camshafts installed and correctly aligned with each other.
Installing camshaft bearing caps.
Reinstalling the timing belt and pulleys.
All other components then got reinstalled including the cam end bearing covers, fuel pump, vacuum pump, timing cover, intake manifold, fuel lines and everything else needed to get it running.
First drive out to the service station. It started up straight away and drove perfectly.
Wires of the manual shift sensors reversed on the shifter circuit board to flip the signal sent to the car computer.
The plus and minus symbols reversed on the trim piece so the graphics match the new shifting layout.
Fitting the shifter trim and centre console back together.
Replacing the upper torque rod mount because the rubber bushing in the old one was split and worn out.
The A/C wasn't working and when I took the compressor clutch off the magnetic coil just fell out. It had clearly overheated, I'm guessing because the ball bearing got old and worn and overheated and the extra heat was too much for the coil.
After taking the magnet housing off I found that the pulley bearing had actually seized spun on the aluminium shaft, slightly damaging it.
I was able to buy a new bearing and clutch coil instead of buying a whole new compressor. I used some green Loctite to hold the new bearing on the shaft which worked well.
Compressor refitted to the engine block and the belts replaced with new ones. Later I got the A/C system recharged with refrigerant and it works perfectly.
