2tg/3t hybrid problem

[anty109]

Hi I just bought this 2tg engine that has a 3t crank in it and 1mm over size pistons so 86mm bores. I turned the engine over bye hand on the stand just to check i got the timing chain right and that the engine turned over with no interference.
All was ok. Started the engine up and all was good then a tapping noise started up. I rechecked the timing chain and made sure the cam caps were tight. Started engine again and it was ok no noise. When i rev the engine the tapping noise comes back. When the head was off i had double valve springs installed and the head was checked and everything was ok. The valve reliefs on the pistons looked like they had some markings on them but the valves were fine so i thought nothing of it.
I used a cometic head gasket H0894SP7043F which is .043'' thick. apparently engine was running fine and was used for a couple of races and the head was pulled off to check compression ratio for a possible turbo conversion. and then i bought it and reassembled it.

does anyone know what the noise could be or what to check from here.

[stidnam]

get some of that clearance dough stuff and put it on the top of the piston and rotate to see how much clearance you have between top of piston and the valve. Could be rod bearing also? but then you should hear it all the time

[71TA22]

Have you checked the valve clearance at the camshafts?

Is the valve timing correct?

[petergoudie]

If it has a mechanical fuel pump driven off the cams or a dummy shaft these can give a tapping noise. When pressurised the pump arm is held off the cam or lightly touches it which can give a tapping noise.

[anty109]

It has an electric fuel pump and ive checked the valve clearance last night and they were within spec. I ran the engine with the rocker cover off and it looks like the buckets on the intake side are being lubricated but on the exhaust side doesn't seem to have oil around them.

[anty109]

Also have checked the valve timing and its set up as per manual. Crankshaft at TDC and both cam slits facing upwards.

[petergoudie]

It would appear you might have a blockage somewhere. Did you check if the new head gasket had all the same holes punched as the original. You might have to remove the camshaft and look to see if any of the oil holes are blocked.

I have no knowledge of your engine model but on one of my Toyotas the oil comes up through the front cam bearing. Is it possible the oil seal has been pushed in too far and covered the oil hole hence cutting off the oil to the camshaft.

[TA22 GT]

There should be oil on both inlet and exhaust cam buckets. Are you certain theres no blockage on the exhaust side can? You should see oil comin out from each of the cam bearings...

[anty109]

The engine is out of the car now. ill check the oil passages. Thanks for all the suggestions I'll let you know when i find the problem

[TA22 GT]

Most likely not this, but if the block was orignally 2T then check the last 3 bearings are blocked where the dummy cam is. These are only used for single cam, for a2Tg they must be blocked. If not, you will not have oil pressure and you could get this type of problem...you need to sump off to check....

[71TA22]

You say you had double valve springs installed. Was this to a 88220 or 88222 head which had single springs previously?

You should install the twin springs with the correct twin spring seat not the single spring seat.

If the exhaust cam buckets and bearings are not being oiled (but the intake sides are) you could have a blocked oil gallery in the exhaust camshaft or the gallery between the exhaust camshaft no 1 bearing and the oil nozzle.

Is the slot on the face of the oil nozzle horizontal?

[anty109]

I didn't find anything obvious wrong with the engine, until i pulled the pistons out. There is alot of wear marks on the skirts of the pistons and on the cylinder wall. I'm going to speak to my local engine builder on Monday.
But if there is wear marks on the piston skirts that means that the piston has moved in the cylinder and hit the side of the cylinder causing the noise?

It doesn't make sense to me because the piston fits tight into the cylinder and there isn't movement when you try to move it with your hand.

[TA22 GT]

Sounds like the pistons are the problem. Could be either too tighter clearance between pistons and bore or not enough clearance on the rings. Piston to bore for forged pistons should be around 3 thou and ring gaps around 20 thou, obviously this depends on piston type. Typically forged piston clearance is measured towards the base of the skirt as this is the widest section, if measured closer to te top then the clearance will be too tight

[anty109]

Yeh sounds like its the pistons. Im taking it to the engine builders tomorrow. Im wanting to cahnge to sr20 det rods and then go a wiseco piston with a pin height of 22mm. Apparently this is a good combo, brian gt has done it. Im just trying to get the part numbers off him

[TA22 GT]

Im building my 3TGTE right now, using Wiseco 87mm with eagle rods.
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