1991 745T Mods and Upgrades
#141
#142
Pistons are fine, but you gotta get all that carbon out of there, a shop vac wil do it.
I've NEVER seen an intake seat drop, it's always exhaust due to the heat. This is a very rare occurence, truly unlucky! The only way I can think it'd happen is a badly reconditioned head......
There does seem to be a very light discolouring between two fire rings on that head gasket, that and the 3/4 fire ring area looks suspect too. I think your head gasket was about to go, or had already partially gone. There's also a chance teh seats on #1 are gone too, causing a combustion leak.
Thinking back, mine gave symptoms for months, but they were very subtle. Like an occasional misfire idling etc.
Make sure you use new head bolts, or if in your budget, ARP studs when replacing the head. It's just cheap insurance with more boost than stock.
Regards, Andrew.
I've NEVER seen an intake seat drop, it's always exhaust due to the heat. This is a very rare occurence, truly unlucky! The only way I can think it'd happen is a badly reconditioned head......
There does seem to be a very light discolouring between two fire rings on that head gasket, that and the 3/4 fire ring area looks suspect too. I think your head gasket was about to go, or had already partially gone. There's also a chance teh seats on #1 are gone too, causing a combustion leak.
Thinking back, mine gave symptoms for months, but they were very subtle. Like an occasional misfire idling etc.
Make sure you use new head bolts, or if in your budget, ARP studs when replacing the head. It's just cheap insurance with more boost than stock.
Regards, Andrew.
#143
bad photos taken at night with a flash.
Thanks for the info Andrew,
Yes, everything is going to get a good clean up, and ARP studs are probably going to get looked into. we still need to look things over when the daylight is out, then, i need to talk with my friend about a head.
at this point... I would love to take out the block and do a full rebuild.
Edit://
we did check codes before the head removal, and got 3-1-2 (i think i poseted this early). Thinking maybe knock issue???
Thanks for the info Andrew,
Yes, everything is going to get a good clean up, and ARP studs are probably going to get looked into. we still need to look things over when the daylight is out, then, i need to talk with my friend about a head.
at this point... I would love to take out the block and do a full rebuild.
Edit://
we did check codes before the head removal, and got 3-1-2 (i think i poseted this early). Thinking maybe knock issue???
Last edited by TIPSP; 11-08-2009 at 03:02 AM.
#144
I don't see any evidence of detonation on anything there, fuelling looks like it was good too, if anything a little rich, just like my car with teh chips.
The exhaust valves are a nice brown colour, if the engine had been running lean for any length of time, they'd be white.
Detonation won't affect valve seats, it really is just a very unlucky thing or bad workmanship in the past.
Code 312 means there is no signal from the knock sensor (knock enrichment disabled) but with Fred's chips, and looking at those photos, it was not an issue (but you should fix it).
Regards, Andrew.
The exhaust valves are a nice brown colour, if the engine had been running lean for any length of time, they'd be white.
Detonation won't affect valve seats, it really is just a very unlucky thing or bad workmanship in the past.
Code 312 means there is no signal from the knock sensor (knock enrichment disabled) but with Fred's chips, and looking at those photos, it was not an issue (but you should fix it).
Regards, Andrew.
#146
#149
#152
I see teh cracks in your cylinder head, that explains the dropped valve seat.
I would be thinking about any overheat events the car has had, or perhaps been low on coolant and driven for some time. You have to REALLY overheat a cylinder head a lot to get those cracks. And you might not really have noticed it either, you can have decent steam pockets in a cylinder head and not really have any indications, if driving normally.
Your cylinders, you should thoroughly clean them to get rid of all the cleaning residue. I like to use paper towel and some spray oil like WD40 (WD40 dissolves the carbon nicely too). Hose the bores down with the oil, wipe UPWARDS with the towels. Move to next bore, repeat. Always turn piston to BDC when doing this, and go through them all 3 times. This way, as you rotate the engine over, the top piston ring cleans up all the light carbon etc and deposits it up high on the cylinder walls. Stop cleaning when the paper towels keep coming out clean, then oil the bores with engine oil and stuff clean oily rags into the bores(stops corrosion).
It may be a little paranoid, but carbon is very hard and a good chunk can score a bore easily.
When you have your cylinder block deck clean as you think it can be, get yourself a wood chisel and scrape it with that. I guarantee you'll get more gasket etc off. Use the chisel pointed away from you, in good long strokes and with a shallow angle to the head. You won't mark cast iron with the chisel, it's good and hard.
I also clean the cylinder deck twice with lacquer thinners and clean rags just before the gasket goes on, leaving it oiled until that stage. I also find scrubbing with coarse steel wool and lacquer thinners brings the cylinder deck up really well. Don't worry about the lacquer thinners in the bores, it'll evaporate or burn off first couple of power strokes.
Regards, Andrew.
#153
there is no crack on number 2 though... the only cracks is on number 1 and number 4.
My mom did overheat this head, many, many, many years ago. the car was never the "same".
We are talking with some people about new heads, so hopefully we can get one in soon.
My mom did overheat this head, many, many, many years ago. the car was never the "same".
We are talking with some people about new heads, so hopefully we can get one in soon.
Last edited by TIPSP; 11-09-2009 at 10:19 PM.
#155
I bought it off of a guy I know. I got the whole interior for ~$175!
Oh, the headliner was done by a prof for about ~$220.
Junkyard should have parts for cheap.
Oh, the headliner was done by a prof for about ~$220.
Junkyard should have parts for cheap.
Last edited by TIPSP; 11-11-2009 at 11:08 PM.
#156
Slight update
Started to clean up everything in the bay, and replace some things that really need to be replaced.
Slightly polished a few of the parts while cleaning them. ran out of engine degreaser...
Cute little turbo...
found some cracks in the exhaust housing. luckly it still seals great. upgrade in the near future.
Throttle body was pretty clean, but had to clean it just because.
Got in a bunch of parts to finish the 740. still waiting on the head to get in.
Also got in the 240 brakes stuff. everything is going to be new, along with SS brake lines.
Happy Thanksgiving fellow Brickers.
Slightly polished a few of the parts while cleaning them. ran out of engine degreaser...
Cute little turbo...
found some cracks in the exhaust housing. luckly it still seals great. upgrade in the near future.
Throttle body was pretty clean, but had to clean it just because.
Got in a bunch of parts to finish the 740. still waiting on the head to get in.
Also got in the 240 brakes stuff. everything is going to be new, along with SS brake lines.
Happy Thanksgiving fellow Brickers.
#158