Leak down test

driller

driller

Dedicated LVC Member
Joined
Mar 21, 2004
Messages
3,815
Reaction score
82
Location
West Virginia
To recap the compression test...


1-195
2-192
3-180
4-185
5-190
6-140
7-150
8-192



Today the results of the leak down test confirm problems with cylinders 6 & 7...


1-90/84 6.6%
2-90/88 2.2%
3-90/86 4.4%
4-90/84 6.6%
5-90/84 6.6%
6-90/48 46.6%
7-90/58 35.5%
8-90/88 2.2%



I could not determine the source of the leakage in cylinders 6&7 via the leak down apparatus. Hooking up 40 psi shop air to the suspect cylinders indicated leakage to the crankcase. :mad:
 
I had conceded the engine had to come out, but I was hoping it was a head gasket issue. This is almost worst case and a huge setback.

I think I'll dump some Rislone in and sell the bitch.
 
I'll give you $1000 for it. ;)

Seriously though, I'm sorry to hear about this. You have any kind of warranty?
 
Have you talked to engine builder yet? Did the peeps that machined parts put engine together?
 
The engine will have to come out and the heads removed for an autopsy. The short block was built by one shop and the long block was put together and installed by another.
 
I hate to hear this for you. Keep us posted on results. I'm trying to guess whats wrong.
 
Did you try putting a teaspoon of oil down the cylinders? If you do that, and the cylinder pressure comes up, you have bad rings.
 
Maybe its something simple like the rings gaps are all near each other.
 
Psychostang said:
Did you try putting a teaspoon of oil down the cylinders? If you do that, and the cylinder pressure comes up, you have bad rings.
Click to expand...

I did not do a wet test, with that much compression loss on 2 adjacent cylinders I was assuming the head gasket. Do you think I should go back and try a wet test?

LaserSVT said:
Maybe its something simple like the rings gaps are all near each other.
Click to expand...

OK, if so I must play the lottery since I have 2 cylinders showing near the same compression loss.

The more I think about it the more confused I become. I could see one cylinder being down but two? And two adjacent cylinders?? At first it was logical to be a head gasket but nothing seems logical now.
 
If he is hearing air in crankcase does not matter if you do a wet test or not. The problrm is to the rings thats why he hears it in crankcase. The decks of mod engines are not sealed underneath the intake like a 302. So if mod HG did breach out on 6 an 7 it would breach to atmosphere.
 
I only mention it cause it happens. Have a dude with a Civic that was low on three and two turned out to be due to the rings not being set right. Third was due to valve dammage.
 
driller said:
The engine will have to come out and the heads removed for an autopsy. The short block was built by one shop and the long block was put together and installed by another.
Click to expand...

When they built the short block was the machining and assembly done with torque plates in place?
I know the cast blocks are a little more forgiving than aluminum but for a big bore mod motor or any mod motor you plan on making big power with I would leave them on all the way through ring fitting to final assembly.
 
97MarkJA said:
When they built the short block was the machining and assembly done with torque plates in place?
Click to expand...

I presume whatever specifics the pros do, it was done with the build of the short block. They build motors that run much more HP than I'm running.

I will talk to both shops this coming week but the bottom line is the motor will have to come out and be looked at. :(
 
I'd be one pissed off mothertrucker. Chit, things of smaller concern than this piss me off, but I rage a lot. :shifty:
 
When I started looking for a shop to do my machine work I found that none here have plates for a 4.6/5.4
I called pretty much every machine shop from hudson wi. To fargo nd.
so thats what I got for christmas.. Nice set of torque plates from ccaracing.
I would have thought that with the mod motor platform most shops would have them, I was told for a basic non performance build they dont need them, performance parts are expensive so they rarely if ever see a performance build.
 
97MarkJA said:
When I started looking for a shop to do my machine work I found that none here have plates for a 4.6/5.4
I called pretty much every machine shop from hudson wi. To fargo nd.
so thats what I got for christmas.. Nice set of torque plates from ccaracing.
I would have thought that with the mod motor platform most shops would have them, I was told for a basic non performance build they dont need them, performance parts are expensive so they rarely if ever see a performance build.
Click to expand...

+1... I was told by a very good builder the plates were not needed.
But the large amount of cash that goes into these forged engines, plates should be used one would think.
I would find out if they were used for future reference.

Sorry it has to come apart.....:(
 
ford nut said:
+1... I was told by a very good builder the plates were not needed.
But the large amount of cash that goes into these forged engines, plates should be used one would think.
I would find out if they were used for future reference.

Sorry it has to come apart.....:(
Click to expand...

Yeah for pass car old granny rebuild not needed but most of time hipo 4.6's are getting supercharged/turbo/nos and 500 hp +. You also have to line hone all the alum blocks on rebuild also. You need all hardware that engine will be put together with too. IE if using ARP head and main studs all machine work must be done with those installed.
 
97MarkJA said:
When I started looking for a shop to do my machine work I found that none here have plates for a 4.6/5.4
I called pretty much every machine shop from hudson wi. To fargo nd.
so thats what I got for christmas.. Nice set of torque plates from ccaracing.
I would have thought that with the mod motor platform most shops would have them, I was told for a basic non performance build they dont need them, performance parts are expensive so they rarely if ever see a performance build.
Click to expand...

So you own a setr of plate? If so you rent them out? My local shop says they have them but I have not seen them. Did yours come with headbolt spacers?
 
Right on the Mark said:
So you own a setr of plate? If so you rent them out? My local shop says they have them but I have not seen them. Did yours come with headbolt spacers?
Click to expand...

I do, if I remember correctly they came with the inserts for the spacers. My dad got them for me for Christmas :) he has a Mark as well.
We will rent them to the shop when they do the bore/line bore, it is recommended they are tq to spec with the head gasket in place; head gasket would be discarded and replaced with a duplicate on final assembly.
I have the teksid block so the process would look something like this.. (by memory)
Deck the block.
Tq plate.
Line hone.. bore.. what ever said shop calls it
Crank goes in to spec.
Bore.
Bottom end comes apart for cleaning.
Reassembly.
Rings fitted.
Rods/pistons installed.
Tq plates come off.
Heads go on.
But like you said, if its a normal pass car its not needed. I know gopher machine who built thousands of 5.4 and 4.6 mod motors for the reman market didn't use a single plate on any of them.
 
No machine work is done with crank in place at anytime. Its done with main caps trqed with correct fasteners. Just a FYI for noobs reading, line hone is short for align hone thats done to the main bearing bores of block. Alum blocks "spring" all over the place and need light clean "str8ening" in this area.
 
Right on the Mark said:
No machine work is done with crank in place at anytime. Its done with main caps trqed with correct fasteners. Just a FYI for noobs reading, line hone is short for align hone thats done to the main bearing bores of block. Alum blocks "spring" all over the place and need light clean "str8ening" in this area.
Click to expand...

Correct! Like I said, memory.. and I am getting old as someone kindly pointed out in another thread.
You wouldn't want to hit the crank with the boring bar or have all the garbage raining down on it. Not to mention it will have a large bar through the mains; depending on the machine of coarse.
 
You must log in or register to reply here.

Members online

Total: 109 (members: 3, guests: 106)
Back
Top