odd compression test q&a

[drbowser3]

We had a customer bring in a car, wasn't running all that well. Customer claimed a small amount of water was mixing in with the oil, according to a member of authority on this forum(who also helped assemble the engine), it was just condensation and not to worry about it. Well with repeated oil changes and still water pouring out he brought it to us. We did a compression test, came out a bit low so we decided to check the oil, milkshake. We go to drain the oil, and for the 1st 30 seconds of the drain plug being a few threads loose, water poured out. Then, "yoo-hoo" colored substance followed.

Long-story short, where one of the head studs screwed in, it was cracked from there to a coolant passage on the block deck.

I think all signs point to cracked blocked. Sucks to say, but its not that hard to pull it back out, just machining will be the most costly part.

 

[jdub]

Only thing I can think of is a cracked block

Yep...I'm afraid IJ is once again correct

 

[IJ.]

As I told Dennis on SF I Magged 5 blocks before giving up trying to find a good used one here and ended up buying a new one...

 

[jdub]

All cracked Ian?
Any certain area?

 

[survyor2]

Cracked block is what i think too. The hardest part is going to be finding a good block. Dare I ask how much Toyota is asking for them new? I don't think looking through the junk yard and spending time dissassembling used engines is the best idea. They could be cracked too and I'd be wasting time. I'm going to find the crack in my block before I purchase a new block but I want to start sourcing them now.

You know something stands out in my mind. When I built my engine a year ago I was torqueing down one of my ARP bolts. I was torquing up to 90 in increments. One of the bolts I torqued and I felt the torque tighten up, then fall off, so i kept torqueing and went back up to 90 so i was done. I chalked it up to nothing but maybe it cracked, thus loosening, then i tightened it back up. I have since installed studs and I didn't notice anything this time.

 

[IJ.]

Most were cracked between the bolt holes and the steam holes
(all early blocks)

One was cracked through a main web

another had been over heated to the point the main tunnels had 10 thou difference end to end.

and not a one had usable bores short of a +40 bore job.

 

[HommerSimpson]

was timing cover cut to match block ?

and maybe put some die in coolant then drain then pull apart and inspect...

 

[survyor2]

was timing cover cut to match block ?

and maybe put some die in coolant then drain then pull apart and inspect...

Yes, timing cover was cut to match block. I'll be looking for that crack when I take it apart.

 

[survyor2]

I pulled the head. This job used to take a few days for me. I got it done by myself in 3 hours and 33 minutes. I was too exhausted to thoroughly inspect everything but I think I see something. What do these cracks look like? THis is the only thing I see so far. I will do more inspecting and testing tomorrow.

What I see is hairline and very hard to photograph. The first photo is best because it has more shadowing. I tried to scratch it off but I can't. My fingernail will catch it. I expected bigger but I guess it will expand with the stud in the threads.

(sorry for the double forum posts)

 

[IJ.]

Were the studs wet with coolant?

 

[survyor2]

Were the studs wet with coolant?

no, not that i noticed.

 

[IJ.]

Any other unexplained coolant puddles/wet areas where it shouldn't be?

Also what was the front cup welsh/freeze plug like and was it changed out?

 

[survyor2]

Any other unexplained coolant puddles/wet areas where it shouldn't be?

Also what was the front cup welsh/freeze plug like and was it changed out?

no coolant in the cylinders. no coolant in the top of the head. no coolant anywere it wasn't suppose to be. The front freeze plug? I don't think its been changed out since i had the motor. I replace two on the side that were blown out / coming out.

 

[IJ.]

My bud's 18,000 mile 87t had those cracks and he wanted to save the block so I cleaned the holes with a tap then some thinners, once dry I loctited the studs in to prevent seepage climbing the studs.

The front plug is the only other thing I can think of where Water meets the Oil side of the crankcase.

 

[HommerSimpson]

guess you need a block now...
BUMMMMMMMER.. sorry for ya :{

 

[supratoyota18]

sorry to thread jack but what should the compression be? i just did one yesterday and just wondering

 

[MKIIINA]

165 across the board. check the tsrm

sorry to see those pics man

 

[suprabad]

I can clearly see the cracks you're talking about and I've seen them before.

Hate to say it but I think your going to be best off with another block. As the block gets hotter the crack gets bigger and the pressurized coolant forces it's way through the crack.

I theorize that these types of cracks occur from over-tightening/uneven tightening of head bolts.

Maybe that's the reason Toyota was not inclined to put enough torque on the head bolts. That being said mine are torqued to 82 lbs with no problems, but I move them up in very small increments when installing a head.

 

[survyor2]

LEAK FOUND!

Ok, I pulled the engine/trans out of the car to further inspect it. I didn't find anything unusual at first but then I notced the front freeze plug was a a slight angle. It looked like it still made a good seal. To further test, I capped off the water pump inlet and filled the block with water with red dye. Sure enough, it was that freeze plug.

Was this freeze plug installed wrong? It looks backwards.

So, I can easily fix the freeze plug, but should i replace this block based on the above pictured hairline crack from the stud to the oil hole?

I didn't see any metal in my oil when I drained it, but should I replace the crank/rod bearings? I probably drove it at least 10 miles with a large amount of coolant in my oil. and only hit 18psi boost once.
Thanks,
Dennis

 

[IJ.]

Also what was the front cup welsh/freeze plug like and was it changed out?

Win for the old guy

The plug is the right way around but they're a bitch to get right!

Where is the crack you're talking about?