Replacing my cylinder head

[danielsprague]

I'm getting towards the end of a complete engine rebuild, just coming to tackle my head.

I'm driving a 1993 2.4 non turbo pickup. That's the later model 2L engine (OHC).

The head is cracked on the bridge between the valve seats on three cylinders, and also has a crack from one of the valve seats to the combustion chamber on one cylinder.

The car had no symptoms of a head problem - no oil in the coolant, no spunk in the oil, no corrosion on the pistons. It did use some water, but also had a leaky rad, so I put it down to that. Most of all, it never overheated at all, the temp gague stayed at between 20 and 50% of it's travel at all times.

So I'm going to replace the head, even though it seems to work OK.

I am travelling at the moment, in Pakistan, hence I have three options for a head:

1) a second hand 3L head: about 230 quid
2) repair my head (welding): peanuts
3) a new Chinese made head: about 130 quid

I'm going to get a secondhand 3L head (that's off a 2.8 litre engine). My question is, does the 3L head have the same cracking problems as the 2L head? Looking at it, it seems to have slightly different water channels, hence I imagine it is better than the 2L head.

I'll have new valve guides put in, the valve seats re-polished, and new valves lapped in, then put my old camshaft in (lobes and journals all OK, but will check them with Plastigage), new valve springs, then grind down the valve lifter shims to make up the clearances if necessary, and also shim the valve springs to retain their fitted height, if necessary.

Anything i shoul look out for on the replacement head? (Apart from cracks, of course)

Thanks

Daniel

[Ptarmigan]

hydraulic lock causing cracked head on 3L

Hi all,

I have a similar problem although possibly a different root cause. I seem to have cracked the head on my 1995 2.8 NA Hilux. After a motorway run the car was idling outside the house and decided to start dumpting 3 litres of coolant overboard. After a top up all seemed ok ish but a few days later I stopped for diesel and a coffee for 30 minutes and then the car wouldn`t crank when I went back. Correction, it cranked but then immediately made a big "thunk" noise. I guessed hydraluic lock and took out all the glow plugs in the pi**ing rain with my 18month son helping by throwing all the food / tools / glove box contents out into the rain to amuse himself. After pumping some brown water out of #4? cylinder (closest to the bulkhead) the car started just fine, but with clouds of white smoke. Now the head is off and my hope that it was just a gasket problem has gone out of the window.

At the risk of getting flamed, I didn`t really find anything that fitted, using the search function, so that`s why I`ve posted here in what seems the closest recent thread.

I have basically the same questions about replacing a cracked head:

1) Should I change the head bolts? I mean are they stretch type?
2) Can I re-use the valve springs and other parts into an empty head and just change the guides and valves? It should be cheaper for me.
3) Should I really change the water pump at the same time? Is there some way to test if it`s working properly?
4) I just changed the timing belt 3000km ago....... can I retension it again?

It doesn`t look economic to ship a head from RoughTrax to Brasil so looking to get a "naked" one here for about £500.

Cheers,
Jon

P.S. Good luck Daniel; I wouldn`t want to be stuck so far from home! Sorry I can`t really say the 3L head is any better :-(

[MattF]

1) Should I change the head bolts? I mean are they stretch type?
2) Can I re-use the valve springs and other parts into an empty head and just change the guides and valves? It should be cheaper for me.
3) Should I really change the water pump at the same time? Is there some way to test if it`s working properly?
4) I just changed the timing belt 3000km ago....... can I retension it again?

Yes, you should replace them all. New head bolts are an absolute necessity. You can skimp on the other stuff, but don't then be wondering why you're rebuilding the engine again twelve months down the line for the same or worse a failure.

Not replacing them is false economy.

[Ptarmigan]

How my head rebuild went; parts used etc

I thought I'd post to close of my part of the story, in case someone else would like to know about rebuilds. The truck is now back on the road, with roughly the following approach:

New cylinder head,
New gasket set complete
Old cams moved to the new head
New intake and exhaust valves + guides
New timing belt etc
New rad cap (precaution)
Pressure tested radiator and tests ok so; keep existing radiator and water pump (prohibitive cost to replace) and import the parts for the next preventative service in 6 months.

Things done at the same time:
Clean carbon deposits and oil sludge from turbo
Replace oil, fuel, air filter
Flush cooling system with tap water and flushing solution for 200 miles, then replace with pre-mix coolant.

Things that went wrong:
A/C now refuses to work (not got round to solving it yet)

Good luck all,
Jon