2.25 diesel head rebuild - help!!!

Hi All,

I'm in the process of restoring my 1973 series III diesel, it's a rolling restoration as it's also my daily ride (well it was until I broke it...)

I made a bit of a boob and got water in the engine - I was out in the bad weather before Christmas and hit a puddle far too fast (long story!). The puddle was a foot or two deep (it also claimed a hatchback later that night which didn't get out...) and I hit it going 30-40 mph so whilst the water wasn't deep enough to reach the filter the splash did... it's a K&N style paper jobby so the water went straight into the engine which chugged for a bit then stalled.

Now ideally I should have taken the glow plugs out and cleared the water before starting it again but I was stuck out in the middle of nowhere without tools or light so I tried starting it as it was just a splash of water... after a lot of chugging and spluttering it finally started - whoohoo I thought! I cleared the glow plugs when I got home then went out the next day in daylight and it was kicking out a ton of white smoke, this cleared eventually so I figured it was just water in the fuel or something. No such luck as it did it every time starting from cold then stopped once the engine had warmed up. There was also a definite misfire and a distinct lack of power - it struggled to reach 40!

I googled possible problems (and also checked the thread on here about drowning a diesel) and checked accordingly. The first thing I did was re-torque the cylinder head bolts in case the head had lifted, the large bolts were all fine but of the 5 small bolts holding the rocker shaft down 2 were loose. It turns out the cylinder head threads are partially stripped, feck, what are my options here?

Now onto the cylinder head rebuild, I figured the smoke was probably due to the head gasket blowing as it stopped when the engine warmed up and everything had expanded so I whipped the head off. While it’s off I figure it’s a good time to refurb it, hence this thread… I had planned to do this anyway, just not in January!

With the head and gasket removed the top of the block looks like this:


Apologies for the ****ty photos, it was dark by the time I finished...

There are build ups of rust in what look like water ways:


There are corresponding holes in the head gasket but the holes in the engine are solid rust - should these be clear?!

Also the inside of the head is rusty, here's the thermostat housing:



The water coming out of the radiator was a nice clear green colour, not a rusty brown as you'd expect from the pics above.

So in summary, what's the diagnosis for the head? two threads are stripped and the water ways are rusty as - can this be fixed or is it fooked?

Also, what does the future for the block look like? Do I have blocked waterways? Is this also fooked?

Thanks in advance, more pics to come as I hopefully rebuild this thing!

Also, cylinder head bolt number 2 was covered in oil whereas the other 8 on that side were dry - it this a problem?!

When you say cylinder head threads are stripped where exactly are they? I may be possible to Helicoil them. Because you ingested water turn the engine over to top dead centre and carefully measure down from block to piston. Turn over 180 degrees and check the other two pistons. Any differences may indicate a bent conrod. Remove all the pushrods and check if any are bent. With luck you will be OK.

Clean the head up and very carefully check the hot spots for cracks and see if they are tight in the head. If all is well carry on and do valves/guides etc.

When you rebuild remove injectors after warm up and re torque the head, do again after 500 or so miles. I know it is a pain but does not take long whilst the tools are out and prevents the head gasket blowing across the push rod area.

Thanks for the reply, assuming the head is usable I'm going to have at it with a wire brush (carefully!) and paint the outside in high temp paint. I need to get some fine sand paper/wet and dry for the mating surface, or I may get it skimmed. What's the best way to clean the inside of the waterways?

The threads are for the bolts which hold the rocker shaft down, there are 5 clamps with 1 small and 1 large bolt each, it's the 3rd and 5th small bolt as you look at the engine from the front. It must have been like it when I bought it and it was running fine so I assume it's not a major issue - but best to fix it! They should be tightened to 18 lbf.ft would a helicoil work with this?

The push rods seem fine, I'll measure the pistons like you said - hopefully the con rods are also fine! Need to buy a bloody big spanner first to turn the engine...

Will take the valves out too to check them then regrind them.

Hose pipe for waterways,helicoil will be fine, is it a metric or imperial head? A starting handle is cheaper option than big spanner but you will need the spanner one day when the rest comes to bits (it will at some stage). If you renew valve guides try and avoid Britpart, I fitted them to mine and had to ream every exhaust guide as they are slightly to big on outside and closed up the hole in the guide. If you skim the head make sure the hotspots are tight or they may lift and course damage or machine operator injury when ground over. The hotspots should be flush to the head face plus or minus 0.002" so look carefully.

Thanks, the head is imperial, will try a helicoil.

I don't have a starting handle so would need to buy one anyway - don't suppose you know what size I need?

The valves look ok so may have been replaced at some point - hopefully I won't need to replace guides - whatever I do replace I will steer clear of Britpart as I've heard nothing but bad things about them...

I need to check the hotspots as I don't think they're flush - can they be moved or should they be replaced? I'm putting a shopping list together

Starting handle available from Paddocks at around £11 Useful for setting tappets but you won't start the engine with one. Hot spots available at around £20 each remove any loose or suspect ones, if the fitting diameter on the head is oversize and they wobble around not a lot can be done at home. They need to be flush to within a couple of thou so that the head gasket holds them in, they are located with a small roll pin type of dowel.

Thanks, I'll check the hotspots at the weekend, got a feeling I'll need new ones - would running the engine after water logging have pushed the hotspots further into the head? What are the consequences of the hotspots being in the wrong place?

I've checked the valves and rockers, all but one seem fine, one of the valves has a groove worn in the top:


And the rocker is worn too:


Any ideas why only 1 of the 8 valves is like this? Could it also be a consequence of the water?

Should I replace all valves and rockers or just the worn one? Anything else to replace whilst I'm in there?

Cheers

Not all of the holes in the head gasket are used, so you will get a rusty trace on the block and on the head.

As far as the waterways are concerned, once again you will get a bit of rust developing, so the best thing to do is to use an old flat screwdriver to scrape it off.

I have never used a wire brush as, depending on what the wire is it can scratch the mating surfaces ... Not good!

In the stat housing, just scrape off any loose-ish crud, but don't go to town on it!

The one valve stem with the groove in should be replaced, as the surface area is in contact with the rocker, which could possibly wear away the rocker foot as the valve rotates.

It is extremely doubtful if the immersion has caused the groove, as it would take a long time to affect the hard surface of the valve.

It is OK to replace a single valve as long as you lap it in correctly.

Oldseadog said:

Not all of the holes in the head gasket are used, so you will get a rusty trace on the block and on the head.

As far as the waterways are concerned, once again you will get a bit of rust developing, so the best thing to do is to use an old flat screwdriver to scrape it off.

I have never used a wire brush as, depending on what the wire is it can scratch the mating surfaces ... Not good!

In the stat housing, just scrape off any loose-ish crud, but don't go to town on it!

Click to expand...

I agree, those waterways are no problem, just clear out any loose stuff and flush with a hosepipe.
Also agree about the wire brush, I have not heard this is good for mating faces. I always carefully use a sharp scraper, held at a low angle to the head, not had a problem doing this.
OP, re. hotspots. I doubt whether water has moved them but they do crack and wear out in use. you can press new ones into the head, you will need to very carefully clean out the recesses in the head before fitting the new ones. Then check the protrusion. If they stick out too much they can crack the head, if they don't stick out enough, they will not be properly supported by the inserts in the head gasket.

Ok cool, the rusty spots are nothing serious then I'll scrape/sand them off as best I can without damaging anything.

I'll clean what I can with the rust - the wire brush is just for the outside so I can paint it - just to make it look pretty more than anything else.

I only intend to do this once (famous last words) so will be doing everything properly, re lapping valves and replacing worn parts etc...

I've just found that the famous Turner Engineering is just down the road from me so I'll be popping in with a shopping list

Thanks again for all the help!

You're welcome

Keep us informed re progress.

Will do

One more question... regarding the helicoil mentioned earlier - I've had a look and they're bleeding expensive! As I'd have to drill and tap the hole for the helicoil anyway, could I just fit a bigger bolt? Or would this cause other problems? The bolt in question is one of the smaller rocker shaft bolts.

Before you start drilling and tapping for helicoils, get a bolt and cut two or three slots at right angles to and through the threads.

Once you have run that up and down a couple f times it might be enough to clean out the threads in the head.

Then see how far into the tapped hole a new bolt will go and compare the length sticking out with doing the same on one of the 'good' holes.

You might be surprised how much spare room there could be ... often enough for the new bolts.

Remember that you will only be torquing them down to less than 20 ft/lbs!

Thanks, I'll give that a go before drilling/tapping anything.

I think the problem is stripped threads rather than dirt etc as the bolts will tighten so far then pop/click and lose all torque - can't get them anywhere near 18lbf.ft.

There is no reason why you can't drill and tap to a larger size as long as you have sufficient room in the pedestals for the larger holes.

Cool cheers looks like I've got my work cut out this weekend...

Just a thought, don't know if this is a good idea or not.

Since the torque is pretty low, I wonder if you could chop the head off and epoxy it in as a stud, using the existing threads as a guide should mean it is straight. then use a nut on the top.

trax said:

Just a thought, don't know if this is a good idea or not.

Since the torque is pretty low, I wonder if you could chop the head off and epoxy it in as a stud, using the existing threads as a guide should mean it is straight. then use a nut on the top.

Click to expand...

Not sure, would the epoxy stand the heat?

I can see future me (or the next owner) swearing at this during a future repair lol

Freetime101 said:

Not sure, would the epoxy stand the heat?

I can see future me (or the next owner) swearing at this during a future repair lol

Click to expand...

should withstand the heat.

haha, yes i can see swearing too :lol: