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no compression fresh build! new HG?


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Morning Guys,

some sad news on my NA-T build. basically got absolutely 0 compression on 2 cylinders and low compression on 2. last 2 cylinders are fine. I've done the checks (oil down the wells) and confirmed its not bottom end (phew). Checked timing and it's all timed up correctly.

Hooked compressor up to the SP wells with a bung and blew 30 psi in there, you could feel the air rushing out of the intake manifold which narrows it down to valves. The cams aren't touching the buckets and it's not holding any sort of pressure still.

I didn't lap the valves, the machine shop did. The only thing i've done is assemble the head after numbering each bucket and valve then sending all of it to the machine shop to get the head decked and valves lapped. 

Anyways, i've got another head on the engine that came out of the supra (both non vvti GEs). I plan to do a leak down test on the dodgy head and confirm its the valves, then swap the other head on provided the decked surface is ok.

Just wanted to ask if i needed a new GTE head gasket, as it relies on squish, and I'm on ARP head studs which i think is a higher torque spec? Can someone confirm? I'd also like to think opinions on using the other head. 

Edited by Nathanj1142 (see edit history)
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Id use the same gasket to put your temp head on and test with that. Then once the problem is resolved again test with the same head gasket to make sure it all works as expected.

Finally take the head off and clean up both surfaces before installing a brand new head gasket.

Be thankful you found this now and not at a later date. Also good job you are using ARP bolts too or you would be going through head studs like you were funding Toyota for the next year :)

Edited by T2 MSW (see edit history)
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2 hours ago, T2 MSW said:

Id use the same gasket to put your temp head on and test with that. Then once the problem is resolved again test with the same head gasket to make sure it all works as expected.

Finally take the head off and clean up both surfaces before installing a brand new head gasket.

Be thankful you found this now and not at a later date. Also good job you are using ARP bolts too or you would be going through head studs like you were funding Toyota for the next year :)

hi mate,

thanks for that! I managed to get the head off last night and found my issue. shining a light into the ports you could actually see the light through the valve seats. Taking some valves out, cleaning the mating surfaces, and putting them back in then doing the petrol test actually 'solved' the issue. I'm suspecting its a case of poor cleaning on my part, or possibly crap thats just been dislodged when ive cranked it over and got stuck.

Taking the head to my mates shop tonight and we're going to steam clean everything. Going to douse the valves in break cleaner before reassembling on a clean surface, then do the petrol test across all 6 cylinders.

Shame i've got to get another HG but rather spend the money now than pay for it later.

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Thats disappointing but yes deffo get everything clean before testing again. and Id use that old head gasket to test it.

It would prob be fine so take someone else input too, its not had a heat cycle through it so its prob still quite clean right now? You will kick yourself if you re-assemble it all and then get a HG leak.

Positive you found the issue though and hopefully thats your one and only over and done with. 

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Just an update:

ive Steam cleaned the head and made sure everything is fine and it’s still leaking when I put water in the valve seats are. Tried using cutting compound and lapping the valves but still no gusto.

going to take it to a friend tomorrow as he’s done head work on a 2j himself. You can see here one valve after lapping is clearly not sitting right. This is the case across a few valves.

C45E89AF-8103-40BD-90C7-FBD3475DEEDF.jpeg

0168D9DB-69D1-472E-916E-B9A8D8A60BCF.jpeg

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I’ve taken the head back to the machine shop. They’re going to pressure test and sort something out for me. Pretty piss poor I thought they would have pressure tested after machining the valves and seats to confirm it’s fine - considering I asked them to check and measure the components for tolerance before machine work as I got it second hand 

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38 minutes ago, Nathanj1142 said:

I’ve taken the head back to the machine shop. They’re going to pressure test and sort something out for me. Pretty piss poor I thought they would have pressure tested after machining the valves and seats to confirm it’s fine - considering I asked them to check and measure the components for tolerance before machine work as I got it second hand 

They should have tested it after doing the work as to ensure the work they have completed is satisfactory. Can’t believe they wouldn’t do it as a matter of course on any head build really 🤷🏻‍♂️ 

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40 minutes ago, Nathanj1142 said:

I’ve taken the head back to the machine shop. They’re going to pressure test and sort something out for me. Pretty piss poor I thought they would have pressure tested after machining the valves and seats to confirm it’s fine - considering I asked them to check and measure the components for tolerance before machine work as I got it second hand 

Nathan, do you mind saying what the machine shop's name is (privately if you want) as I've got a spare head i want checking over by someone in the Hull area (which i assume these are) and it sounds like they're one to avoid!

Edited by jim_supra (see edit history)
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Just now, jim_supra said:

Nathan, do you mind saying what the machine shop's name is (privately if you want) as I've got a spare head i want checking over by someone in the Hull are (which i assume these are) and it sounds like they're one to avoid!

No lies mate just got a phone call back from them and they’ve pressure tested the head and there’s no leaks. I’m honestly baffled. I must have had crap stuck behind the seats or something I’m not sure. I’m happy with their service now considering they offered to do that for free, but Upto you if you trust them.

yorkshire engines (ltd) or genesis engines (same place down spring bank)
 

 

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Thanks, I know Genesis. I used them to do the cylinder head that is currently on the car with no issues all, then i sent them my block to do and they went bust part way through! Thankfully at the point they went bust they'd already stripped, cleaned, checked the block and honed the bores, plus had polished the crank so i just had to re-assemble everything. Didn't know they were back up and running, though my dealings with them were a couple of years ago now.

Very odd that they're saying there is no issues with yours, hopefully it's sorted though now and can go back on the car.

 

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2 hours ago, jim_supra said:

Thanks, I know Genesis. I used them to do the cylinder head that is currently on the car with no issues all, then i sent them my block to do and they went bust part way through! Thankfully at the point they went bust they'd already stripped, cleaned, checked the block and honed the bores, plus had polished the crank so i just had to re-assemble everything. Didn't know they were back up and running, though my dealings with them were a couple of years ago now.

Very odd that they're saying there is no issues with yours, hopefully it's sorted though now and can go back on the car.

 

I don’t think they’re bad - they seem to know their stuff I just have no idea what’s going wrong and all the fingers point at their machine work. 
 

gonna go pick it up tomorrow, reassemble then stick on the car and blow the compressor into the spark plug wells again to save me timing it up to make sure.

got a HG requested from TCB so hopefully won’t be long and I can get her cranking again!

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Hi mate did the valve in the picture lap back in ok in the end like or are the seats needing recutting did they not test the head at all then and are they moving through the guides ok   Are they still leaking then or low compression at that cylinder what clearances and valve lash you getting with that bucket and shim at the cylinder    
    Feel for you mate been so close to getting her started then this they should of pressure tested it and saved you some £

   

  

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On 3/28/2021 at 7:56 AM, Dan8 said:

Hi mate did the valve in the picture lap back in ok in the end like or are the seats needing recutting did they not test the head at all then and are they moving through the guides ok   Are they still leaking then or low compression at that cylinder what clearances and valve lash you getting with that bucket and shim at the cylinder    
    Feel for you mate been so close to getting her started then this they should of pressure tested it and saved you some £

   

  

They probably did test it quickly as they said their machine was 'well in the green'.

 didn't time up the engine, i just left the spark plugs out and tested each cylinder one by one by cranking for half a second to a second. Ideally i would be looking for a similar reading across all cylinders. I think cylinder 1 got to about 50 psi in 3 steps whereas cylinder 3 got to 80 odd psi in one step... It was a similar story before i took it back but was much worse.

I did pay for the valves to be lapped or machined, i just requested whatever needs to be done. I think the seats aren't quite straight? I've pulled apart my other head and lapped all the valves by hand, the head gasket was in great condition as was the decked surface, and the valves had an even seat all the way round. I tested with petrol and had no leaks, unlike the dodgy head. I've ordered some stem seals from whifbitz - just need my new HG from TCB and should be back where i was! I'm just thankful i had another head.

 

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33 minutes ago, Nathanj1142 said:

They probably did test it quickly as they said their machine was 'well in the green'.

 didn't time up the engine, i just left the spark plugs out and tested each cylinder one by one by cranking for half a second to a second. Ideally i would be looking for a similar reading across all cylinders. I think cylinder 1 got to about 50 psi in 3 steps whereas cylinder 3 got to 80 odd psi in one step... It was a similar story before i took it back but was much worse.

I did pay for the valves to be lapped or machined, i just requested whatever needs to be done. I think the seats aren't quite straight? I've pulled apart my other head and lapped all the valves by hand, the head gasket was in great condition as was the decked surface, and the valves had an even seat all the way round. I tested with petrol and had no leaks, unlike the dodgy head. I've ordered some stem seals from whifbitz - just need my new HG from TCB and should be back where i was! I'm just thankful i had another head.

 

Hi Nathan.

When doing the compression test, did you only crank the engine for 1/2 second for each cylinder?

I crank the engine 5-7 times for each cylinder when I do compression tests.

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33 minutes ago, Mgrene said:

Hi Nathan.

When doing the compression test, did you only crank the engine for 1/2 second for each cylinder?

I crank the engine 5-7 times for each cylinder when I do compression tests.

I would normally do this mate, however as i said i wasn't getting consistent readings across the cylinders. I also hooked the airline up in the sparkplug wells and blew 50psi and could hear and feel it coming out the intake port still on cylinder 1. 

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