Engine Rebuild? What went wrong????

vwbill · Post by **vwbill** » Wed May 05, 2004 10:50 pm

Hey, well I get the intake leaks fixed at the intake hose boots then take it for a ride just to have the sound of a exhaust leak about a mile down the road then it starts sounding worst!! I check all the exhaust nuts(one a little loose) but it sounds too loud to be a loose nut! It sounds like it must be at the heads, I think! I checked the compression and 1-140,2-140,3-128,4,132. So what did I do wrong on the rebuild? Did I screw the cylinder/head seal when I had the timing wrong and had that giant back fire? Well back to square one! Is the T4 engine not a regular manual rebuild guys type engine? I was better off when the motor had the hole in the side edge of the number one cylinder!! It ran better just noisey!
So what's the deal with the rebuilders/remanufactured motors? They say they use dished pistons not the domed. I have the 1700Ea fi. Should I just get another 1700 rebuild with the dished or can I get the 1800 and use my fi system or a 2000 and my system? The cost is basically the same. Can I get my engine rebuilt and keep My domed pistons or is it worth it? How much should I spend to fix my lame rebuilding? I've seen 1700 remans for 1220$ up to 2500$ Arrrg!? Can you use rebuilt heads or is new the only way to go? Thanks, Sad times here I cant get ahead in this project! Thx Bill

DeathBus · Post by **DeathBus** » Thu May 06, 2004 6:14 pm

ok so let me get this right, you rebuilt the engine? or was this one that someone else rebuilt?
Anyone can rebuild a Type 4 you just have to know the correct steps.

vwbill · Post by **vwbill** » Thu May 06, 2004 10:12 pm

I had the heads rebuilt/reconditioned. I just did a clean on the pistons and re-ringed and checked the gaps per specs. I cleaned and inspected the other parts; new solid lifters. I didnt split the case just inspected and checked the plays. I've only built up bus 1600 motors from the short block up before but never had a such problem with the head sealing areas. I guess I did something really wrong to get ehaust leaking somewhere. It just seems so weird that by doing my best fit with rebuilt heads I couldnt get it to at least the point prior with the number one cylinder head with a blow out! I guess I need a real rebuilder! Bill
p.s. My fire burnt bus motor never leaked and it ran again with just new rubber parts and electrical!! LOL!

DeathBus · Post by **DeathBus** » Fri May 07, 2004 1:23 am

I have rebuilt many Type 4's no problems, my only type 1 BLEW UP

. Anyway, what you could have done wrong was the tightening of the heads. Type 4 heads torque in a different pattern than type 1's and if torqued wrong can lead to a head leak. Type 4 heads are known to leak anyway, the best way to insure they dont is to LAP the jugs to the heads. Also when you had your backfire you might have also cracked a ring. When the heads were redone did you need new valve guides? Also when the heads were redone did you check the valve seats, they have been known to drop in Type 4's also.

vwbill · Post by **vwbill** » Fri May 07, 2004 12:19 pm

Well I know I torqued the heads right from 412 manual. I dont remember but I think they put new seats in and guides.
I think the problem might be I should have lapped the cylinders to the heads! I know Ray spoke about that! I guess you do it with valve grind compound to set the cylinder better in the head! I just really didnt think it would be that much off! I hope I didnt crack a ring but they were cofabs! I cant get myself to pull the motor for the third time on this rebuild! Argg,lol! Thx Bill

DeathBus · Post by **DeathBus** » Fri May 07, 2004 12:38 pm

vwbill wrote:Well I know I torqued the heads right from 412 manual. I dont remember but I think they put new seats in and guides.
I think the problem might be I should have lapped the cylinders to the heads! I know Ray spoke about that! I guess you do it with valve grind compound to set the cylinder better in the head! I just really didnt think it would be that much off! I hope I didnt crack a ring but they were cofabs! I cant get myself to pull the motor for the third time on this rebuild! Argg,lol! Thx Bill

Yep you use valve lapping compound. Was your engine leaking oil? Thats a good sign of a cracked ring, the blowby will increase the case pressure and you will start pouring oil out of strange places.

raygreenwood · Post by **raygreenwood** » Fri May 07, 2004 9:06 pm

Slow down. This is not a lost cause. The compression listings (individuallY) are not that bad at all. Just not close enough to each other. This could easily be that they are not fully broken in yet. First things first. Check the exhaust manifolds. Check valve adjustment.
Now...take your time. It would be worth it to pull the engine, pull the heads and pull each cylinder at one time and lap it to its spot in the head. If you were happy with your compression...or close to it...put on a .010" base shim (if you do not have one)...and dump the head gasket and put it back together. If you have not put solid inserts in for exhaust studs...do it now. read some of my back posts on this. Do not use helicoils. With what you have for compression...which is good enough for just starting up for used pistons...and the cam is in good shape (didn't die on break in) and you know you did the bottom end right, then this could only be a leaking head gasket or exhaust manifold. Ray

DeathBus · Post by **DeathBus** » Sat May 08, 2004 3:21 am

raygreenwood wrote:Slow down. This is not a lost cause. The compression listings (individuallY) are not that bad at all. Just not close enough to each other. This could easily be that they are not fully broken in yet. First things first. Check the exhaust manifolds. Check valve adjustment.
Now...take your time. It would be worth it to pull the engine, pull the heads and pull each cylinder at one time and lap it to its spot in the head. If you were happy with your compression...or close to it...put on a .010" base shim (if you do not have one)...and dump the head gasket and put it back together. If you have not put solid inserts in for exhaust studs...do it now. read some of my back posts on this. Do not use helicoils. With what you have for compression...which is good enough for just starting up for used pistons...and the cam is in good shape (didn't die on break in) and you know you did the bottom end right, then this could only be a leaking head gasket or exhaust manifold. Ray

I fully agree with Ray, if your engine isnt blowing oil out of every oriface then it is something simple. Timing, valve adjustment, fuel flow, make sure everything is right before you yank the motor. If you have not done so I recomend buying the BUG ME VIDEO TYPE 4 ENGINE REBUILD.

Vgonman · Post by **Vgonman** » Sat May 08, 2004 6:31 am

Does not sound like a lost cause yet IMHO> But, one thing I think you should do, should you pull the motor, is at least verify your oil pressure with a mechacal guage (or if you do not have a spare bell housing starter, hook up a mechanical gauge to the motor, pull the distributor wire, and see what you get) I have gotten into the habit of doing this, and then any question of oil pressure is out of the question.

Another thing, it is not a biggie to split the case, and replace the internal bearings. Without splitting the case on one of these old motors I would at a minimum doubt the cam is in the greatest of shape. All other bearings are not that much$$. There is no way you can know the shape of the rods or crank without splitting. A lot of guesswork and chances taken when not knowing for sure. You sure seem like a guythat is doing all he can do do it right, and do it once. Not splitting seems to be a chancy shortcut.

raygreenwood · Post by **raygreenwood** » Sat May 08, 2004 11:05 am

The dished pistons create a slow, low powered hot running engine. Those are bus parts in a 1.7. To get decent compression with dished pistons, you have to make the deck way too tight for the rims ofthe piston. Thats dangerous. If they are good quality dished pistons, they can probably stand to have most of the edge ofthe dish "lathed" away. Leaving either a very shllow dish or a flat tp. From that point, a reasonable compression (still low for a 1.7) can be made. Its worth it to save/use good domed 1.7 pistons. Ray

vwbill · Post by **vwbill** » Fri Jul 16, 2004 8:20 pm

Well Pulled the car in the garage again to see if I can get back to the motor pullling pulling again, lol! I ran it but the clutch disc was already stickin from sittin! Got it loose after checkin the slave and bleed.....
Man, makes me sick to take it apart when I looked under the motor today it was sweeet dry no oil drops too, loloo!!......
I was thinkin of doing the tdc compressed air to listen for the leaks in the head/cly. must be at the top since no oil. Got to take it down and back check the peices again! Back to the Micrometer and feeler gauge,lol! Too bad there isnt a magic additive that would cad weld the head to the cylinder,lol! How about a bottle of copper for the radiator and compressed air ,lol That should last in a 412 motor! Loll!
I'd get another back fire from hell and blow out the heads,lol.
Well maybe a good saturday and I can post the bad builder dont do this!
I think its better to send it out to the m-shop/builder!
bill

raygreenwood · Post by **raygreenwood** » Fri Jul 16, 2004 9:49 pm

STOP....this is probably simpler than you think. You have massive backfires occasionally? That means you have an intake valve leaking into the manifold...or an exhaust valve leaking compression and raw fuel into the exhaust. Both of those will cause backfires and manifold backfires. Could be a poorly lapped/cut valve...a bent valve......or simply incorrectly adjusted valves. Ray

vwbill · Post by **vwbill** » Sun Jul 18, 2004 12:13 am

Hey Ray, so if I put air in the plug hole and tdc it, I would hear air leaking somewhere then... Under the valve covers or intake tubes or exhaust or head/cylinder edge???? It was stormy here today and I have a car port, so I havent pulled the plugs and fired up the compressor.. I guess I could use my mighty bleeder pump/vac. gauge hard to look and pump!
I just think the heads are coming off and remeasure the rings and bearin clearances at min! then I think I want some kinda head/cylinder gasket!
Maybe copper thin!(Hey what about the gold leave sheet stuff) I want something to form a seal! I dont want to do this again because of connection of surfaces!!! If I could I would weld the damn things! At least It would be operable. But if I have a bad ring now It would be worse! Tomorrow have to work rain or thunder! lol!
bill

raygreenwood · Post by **raygreenwood** » Sun Jul 18, 2004 12:56 am

No...you can't weld them. Also, no...gold leaf will not work. Regardless of a seal or not..you are metal to metal sealing. Did you say you were planning to pull the cylinders again to check the ring gaps? then just lap the cylinders to the head while they are out...its simple....its the best seal there is...short of complex step cutting. Much better than the factory gasket. Unless you truely understand what the ramifications of any liquid sealer are....ie: you have tested it,...leave it alone. So...did you use the factory head gaskets...no? Thats good. Did you lap the head to he jugs? If no...you are expected to leak.

Also...the differences in compression you have are normal....for a brand new no miles ngine. It takes a while for the rings to seat sometimes.
Have you checked valve adjustment when the engine is warmed up to make sure you have gap? Also, what did you have done on the heads? New valves? new seats? just a re-grind? I doubt you will be able to exactly pinpoint a leak from leak down sounds. It naturally leaks past the rings some. Ray

67 T1 · Post by **67 T1** » Sun Jul 18, 2004 7:10 am

Is there a particular thread that details "how to lap". Not at all familar with this process, or even what in means. Did a search that was fairly inconclusive for such a generic term with multiple meanings. thanks

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