[Topgear]

Hi Everyone

I purchased an old 1989 sierra soft top SJ50 for a paddock basher to get my young bloke driving more before his licence. It sat for four or five years unused and have just got it going again. I’ve changed out all oils but after the 1st run it got a little hot and now have water in the oil see photos. I put on a new water pump and timing belt and checked valve clearance and thought it may have just been condensation for sitting so long. I checked it with a cheap leak down tester and all cylinders seemed to show OK on the test, but I don’t have much confidence in the tester!. After cleaning it out and putting it back together it’s definitely water getting into the oil, now also showing on the dipstick and in tappet cover again. It’s got 156 000 km on engine.
I plan on pulling the head off and having a look but anything else I should be looking at that could cause this?

What are the chances it’s just a head gasket failure rather than a cracked head? Also does anyone do exchange G13a heads if the head is cracked?

Thanks for any help/advise people maybe willing to give.

Cheers John

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[sideways]

Cracked head an an 8v G13 is rare, it will likely be the headgasket. It's an easy job to do the gasket.

[Boggomobile]

Hi John,

It is hard to see the Philips head screws in your photos, the ones at the very top (8 off) that hold the rocker shafts in place. In one of your photos there is a screw that looks higher in the countersunk recess? The one closest to number 3 exhaust port might be missing? These sometimes work loose and I was unfortunate enough to have one lodge itself under the cam! Resulting in sunburst fracture in the head that was unrepairable. Not sure if this helps but definitely check that they are tight if the problem is something else and easily fixed.

[Topgear]

Thank you Sideways and Boggomobile

I got the head off this afternoon. As mentioned it sat for a number of years unused with water not coolant and it’s corroded away the head on cylinder 1. It’s eaten the gasket as well as the head. Not sure if a new gasket would fix it due to the corrosion on head? When I got it a few weeks back I dropped the oil and it wasn’t milky so I think the 1st run we did in it was enough for it to let go.

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The block looks ok. No corrosion, but lots of scale but think it will clean up OK.

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One question is this a drain for the block? I’d like to get all the scale out and have taken off the water pump but the gallaries around the pistons are lower than the water pump hole. Might cover things up and blow out with compressed air if it’s not a drain for the block.

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Sideways - yes one of the Phillips head screws had come out. I noticed this when I did the valve clearances when I first got it. I replaced it. Old one was floating around in the tappet cover!

So I think I’m looking for a new recon G13a head. Could give a new gasket and some JB weld a go I suppose is there a preference for head gaskets for these?

Thanks again for everyone’s comments.

Cheers John

[Topgear]

We’ll head does look shot, so looking at options for a replacement. I can’t seem to find a G13a head anywhere. Am I right that other heads like a G13ba or g16a will be a direct fit also?

Anyone have any leads on we’re I might find a replacement head? Tried a few local wreckers but no luck.

Cheers John

[Topgear]

Update
Managed to get a head from suziworld. They sent it up and said to get it skimmed before install. So took it to the local cylinder head rebuild place. They gave it a look over and found a burnt out exhaust valve in the replacement head. No problem, just get one out of the old head. However old head exhaust valves are 30mm and the ones in the new head are 32.5mm.
Worked out (I think) it’s a g16a head. So…. Ok can get a new exhaust valve BUT will this create other issues? I read the fuel pump needs to be different. Also my old camshaft is going in the replacement head, will this be OK?
Old head is marked s-2, replacement s-3.
Anyone able to shed some light on if using this replacement head will create issues or should everything just bolt on?
Appreciate any insights.

Cheers John

[Topgear]

Well just to finish the thread. Suziworld took the g16 head back and sent up a correct g13a head. This saved me a lot of hassle. Managed to get everything back together and running again! Not an overly hard job changing the head. Hardest part was getting all the parts!

Changed out a lot of things as well, water pump, timing belt, hoses and also put in a vitara VC fan.

Hopefully all good for a while now.

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[Erik]

Boggomobile wrote:

Hi John,

It is hard to see the Philips head screws in your photos, the ones at the very top (8 off) that hold the rocker shafts in place. In one of your photos there is a screw that looks higher in the countersunk recess? The one closest to number 3 exhaust port might be missing? These sometimes work loose and I was unfortunate enough to have one lodge itself under the cam! Resulting in sunburst fracture in the head that was unrepairable. Not sure if this helps but definitely check that they are tight if the problem is something else and easily fixed.

I opened up my '94's rocker cover a few weeks ago and 3 screws were out (one lodged down an oil gallery!) and all the rest just loose, sitting there vibrating, doing fuck all - apart from 1 REALLY tight one.

I couldn't believe it could run like that.

[Topgear]

Yep. sounds like a common problem. Pretty easy to pull the tappet cover off and check them so I'll look to do this every once in a while.