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Engine Specific Info and Questions => IDI Engine => Topic started by: andy2 on June 28, 2004, 06:28:46 pm

Title: Head Gasket thickness?
Post by: andy2 on June 28, 2004, 06:28:46 pm

just wondering about this issue, I found a 1.6td that doesn't have mutch blowby and has low compression readings(270-300psi), anyways the head looks like its been off and it has a 3 notch headgasket , Now assuming that the piston potrusion is low enough It might be possible to use the 1 notch gasket :) ,  so from 3 to 1 notch (if possible) , can the gasket thickness make that mutch difference to get it up over 400psi :? ,also is the 3 notch most common for an orignal engine. thanks in advance

Title: Head Gasket thickness?
Post by: DieselsRcool on June 28, 2004, 08:55:59 pm

Could be valves or rings or both. The gasket thickness won't make that much difference. Are they all close together in readings?

Title: Head Gasket thickness?
Post by: Dr. Diesel on June 28, 2004, 10:59:59 pm

you'll have to measure piston projection to determine gasket thickness.
Blacktie's old engine had numbers like that, and it's valves were bent.

Title: Head Gasket thickness?
Post by: VWRacer on June 29, 2004, 07:10:53 am

Andy, the gasket type is determined by how far the pistons project out of the block at TDC. Here are the specs:

Piston Height/Number of Notches
.67-.80mm (.026-.031")/1
.81-.90mm (.032-.035")/2
.91-1.02mm (.036-.040")/3

If the pistons stick up further from that, they will have to be shaved to get them down into that range. If you end up having to overbore the block and install new pistons, you'll have to check their heights and install the correct gasket. If you reuse the same pistons, you should be able to use a 3-notch, but will want to recheck the numbers to be sure.

Title: Head Gasket thickness?
Post by: BlackTieTD on June 29, 2004, 09:29:26 am

Quote from: "Dr. Diesel"

Blacktie's old engine had numbers like that, and it's valves were bent.

the numbers on my old engine were roughly 320-350psi... bent valves across all four.

replaced head with a remanned one, did nothing to the block, new HG and bolts obviously... and the numbers came up above 500psi.

Title: Head Gasket thickness?
Post by: andy2 on June 29, 2004, 08:15:26 pm

Thanks for the replies ,I kind of figured that the gasket thickness couldn't have made that mutch diffrerence towards the Compression ratio, so would the different gaskets be around .010"-.015" different from eachother. my engine with the two notch has 540-560 psi across all four,and roughly has the same amount of blowby as the 270-300psi engine, so the bent or worn valve theroy sounds like it could be the cause ,I'll do a leakdown test and see whats going on.

Title: Head Gasket thickness?
Post by: racer_x on July 02, 2004, 08:05:02 am

Sounds like valve problems to me too.

Is there any way to do a "wet" compression test on a diesel? I know you can't use motor oil in the cylinder because it can ignite, but is there some other fluid that would work to seal the rings and narrow low compression problems down between rings and valves?

Title: Head Gasket thickness?
Post by: fspGTD on July 02, 2004, 11:10:05 am

Quote from: "racer_x"

Is there any way to do a "wet" compression test on a diesel? I know you can't use motor oil in the cylinder because it can ignite, but is there some other fluid that would work to seal the rings and narrow low compression problems down between rings and valves?

Leakdown test.

Title: Head Gasket thickness?
Post by: DieselsRcool on July 02, 2004, 11:55:12 am

Build your own leak down tester.  :D
 
http://www.morrowmarsh.ca/concours/techpages/leakdowntester.htm