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treerootCO
03-02-2010, 01:15 PM
We were replacing the oil pan gasket on my dad's 40 and noticed antifreeze dripping from the #2 cylinder. The piston appears to be steam cleaned so that would confirm that. The head has been machined and a new OEM head gasket was used. The history of this engine is that the #2 exhaust valve was burnt. We can't find any issues with the old head gasket and the 'crack' doesn't really look like a crack anymore in the daylight. We borrowed a machinist straight edge from John and the block and head are straight. Almost looks like where the ring sat but we were hoping for a smoking gun. The head was magnafluxed.

17389

This is the suspect crack:
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Phrog
03-02-2010, 02:39 PM
I agree with your observation that the crack doesn't look like a crack.

Where specifically was the antifreeze coming from? As you know,
water (and antifreeze) can wander around a bit before it decides
to make itself visible.

-Phrog

1972 FJ40
2003 100

MDH33
03-02-2010, 02:41 PM
Wouldn't there a lot more scoring of the wall if antifreeze was mixing with the oil in the cylinder?

Uncle Ben
03-02-2010, 03:34 PM
That line is just too straight to be a crack! Cracks in cyl walls are usually diagonal or vertical not horizontal. Check the valve pocket for a crack! With the valve out it should be clean around the crack. Since the coolant was in the cyl I would check the intake valve seat....possible when they redid the head they cut the seat to deep.

treerootCO
03-02-2010, 07:33 PM
The antifreeze was dripping down the cylinder wall of #2. I was looking up from underneath. When we turned the engine over by hand, a drip squirted past the rings. I will pull the valve tomorrow and look but that sounds like a very possible scenario. One of the head bolts has a slight interference with a helicoil so it might not have been torqued enough so we are going to fix that. We also bought a tap to clean the threads for the head bolts this round. Last time, all we did was clear the holes of debris and turned them in with a small amount of oil on the threads per the FSM. I looked at the 'crack' at night and could catch a knife on it but the more we looked at it today, the less we think that was the antifreeze leak. We tried compressed air from the inside out and nothing went into the water passages.

treerootCO
03-03-2010, 11:43 AM
Nothing visually cracked. This cylinder is very clean so the rust may just be from us cleaning it. Not sure how to pull the seat out to make sure it wsn't drilled to deep or broken behind. We filled the head with water and tried to get compressed air into the water passage and nothing appears to be leaking under atmospheric pressure.

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Uncle Ben
03-03-2010, 12:36 PM
Hopefully your efforts were just a waist of time! I'm "rooting" for ya! ;) :thumb:

treerootCO
03-03-2010, 04:02 PM
Took the head to Mountain High Performance to test it right. $65 seems fair. I don't see anything wrong with the head either.

waggoner5
03-03-2010, 05:44 PM
It all looks good from here. What Kevin said.
Does Toyota stake the exhaust valve seats or is that a machine shop deal?

treerootCO
03-04-2010, 04:45 PM
Machine shop found a crack in the exhaust runner of the #2 cylinder. That is good and bad news because I am relieved we found the problem but now we need a new head. I am still digging out the heads in the garage for those that expressed interest. The machine shop has casting numbers to identify the cross over years.

MDH33
03-04-2010, 04:47 PM
Machine shop found a crack in the exhaust runner of the #2 cylinder. That is good and bad news because I am relieved we found the problem but now we need a new head. I am still digging out the heads in the garage for those that expressed interest. The machine shop has casting numbers to identify the cross over years.

Glad you figured it out Mike. Bummer that you guys just did that head fairly recently though, right?

TIMZTOY
03-04-2010, 08:40 PM
was that block sitting for a while ? that line looks like a piston ring line from were the piston would be sitting for a extended perioded of time.. and the rings fused to the wall. just ideas. but it dosent look like anything to be consirned about

treerootCO
03-05-2010, 11:35 AM
The head was manga fluxed and rebuilt recently. The crack is in a place you can't see according to the machine shop.

17461

http://forum.ih8mud.com/40-55-series-tech/82256-2f-serial-number-info.html

The date code is cast in the block on the manifold side, midway between the last two core plugs.

It is a 5 digit number.
First digit is the year.
Next two digits are the month.
Last two digits are the day of the month.

So your block might have a number like 91217
9= 1979
12= December
17= the 17th

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North engine - 441050 = Mar '80

South engine - 334175 = Dec '78

wesintl
03-05-2010, 11:57 AM
huh?

treerootCO
03-05-2010, 12:34 PM
huh?

Looking for a new head for my dad in the pile of cr@p in the garage.

treerootCO
03-10-2010, 01:11 PM
South = December 4th, 1978

Off to the machine shop.....

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treerootCO
04-05-2010, 05:40 PM
I wanted to update this thread that we dropped a new head off at the machine shop and had it redone. The engine was reassembled and is back up and running. :)

zornff
04-06-2010, 07:20 AM
So when do you get to drop in your new to you tbi 2f ?