Timing Chain Cover Leak
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05-26-2015, 09:51 PM
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Timing Chain Cover Leak
This is the second time I have had a timing chain cover leak, and from the same, passenger side inlet. Is this some sort of inherent design defect? My engine is an Advanced Auto rebuild, but the first engine leaked out the front at 120,000 miles. This engine has about 30,000 miles and it sprung a leak. This is a 1995 Dakota with the 3.9 L V6 engine.
I was losing coolant, about a third of the reservoir bottle, but I could not see the leak. I used a coolant pressure tester to pump up the system and fluid was flooding down the front of the engine face. I initially thought I had a water pump leak, because the shaft is concealed by the serpentine belt pulley.
A new water pump was not the problem, so after taking the fan and shroud out again, pumping the system up and getting my camera in there, what I saw was a leak from the timing chain cover. This is underneath the cover looking up the front of the engine block.
Well to get to the timing chain cover you have to take the harmonic balancer off.
And to get the harmonic balancer off you have to break loose the bolt in the middle. I don't have air tools, which has to be the best way to break the nut loose, so I had to fabricate a tool to bolt to the face of the harmonic balancer to keep the crankshaft in place:
It worked great. I used a 3/4" drive socket and ratchet, and a pipe on the end of the ratchet!.
This is the back side of the timing chain cover. These pictures were from the first timing chain cover leak.
The water inlet ports that go through the timing chain cover are clearly visible on the upper left and right.
Notice the corrosion on the outside of the water passage. The seal had failed long before the leak became intolerable. Now here is the thing, notice that the support bolts are not at 0 degrees and 180 degrees. Bolt support is asymmetrical, more like 45 degrees off any line drawn through the center of the water port. I am of the opinion that this is a bad design, the water port is not evenly supported, but thankfully, when it does leak, it leaks to the outside, and not into the oil pan.
I also noted, once everything was bolted on to the front of the engine, I had AC brackets that bolt to the Timing chain cover, but not to the block. So I have a number of heavy, vibrating things, wobbling the timing chain cover. This is an underneath picture, and there is a A/C bracket bolted to the outside of the timing chain cover.
I did not count just how many A/C bracket bolts go only to the timing chain, but with this amount of weight, I don't think this is good for that joint between the engine block and the timing chain cover.
I don't know if I should have installed the four bolt that support the inlet and outlet with a thread locker or not. Just tonight I went out and checked the tension and found one bolt loose! These water port bolts go directly into the engine block and I think the ends are in the water jacket portion, which I am sure, creates its own issues.
So, are leaks here something that happen often to everyone else, and what do you do to ensure the bolts don't come loose?
I was losing coolant, about a third of the reservoir bottle, but I could not see the leak. I used a coolant pressure tester to pump up the system and fluid was flooding down the front of the engine face. I initially thought I had a water pump leak, because the shaft is concealed by the serpentine belt pulley.
A new water pump was not the problem, so after taking the fan and shroud out again, pumping the system up and getting my camera in there, what I saw was a leak from the timing chain cover. This is underneath the cover looking up the front of the engine block.
Well to get to the timing chain cover you have to take the harmonic balancer off.
And to get the harmonic balancer off you have to break loose the bolt in the middle. I don't have air tools, which has to be the best way to break the nut loose, so I had to fabricate a tool to bolt to the face of the harmonic balancer to keep the crankshaft in place:
It worked great. I used a 3/4" drive socket and ratchet, and a pipe on the end of the ratchet!.
This is the back side of the timing chain cover. These pictures were from the first timing chain cover leak.
The water inlet ports that go through the timing chain cover are clearly visible on the upper left and right.
Notice the corrosion on the outside of the water passage. The seal had failed long before the leak became intolerable. Now here is the thing, notice that the support bolts are not at 0 degrees and 180 degrees. Bolt support is asymmetrical, more like 45 degrees off any line drawn through the center of the water port. I am of the opinion that this is a bad design, the water port is not evenly supported, but thankfully, when it does leak, it leaks to the outside, and not into the oil pan.
I also noted, once everything was bolted on to the front of the engine, I had AC brackets that bolt to the Timing chain cover, but not to the block. So I have a number of heavy, vibrating things, wobbling the timing chain cover. This is an underneath picture, and there is a A/C bracket bolted to the outside of the timing chain cover.
I did not count just how many A/C bracket bolts go only to the timing chain, but with this amount of weight, I don't think this is good for that joint between the engine block and the timing chain cover.
I don't know if I should have installed the four bolt that support the inlet and outlet with a thread locker or not. Just tonight I went out and checked the tension and found one bolt loose! These water port bolts go directly into the engine block and I think the ends are in the water jacket portion, which I am sure, creates its own issues.
So, are leaks here something that happen often to everyone else, and what do you do to ensure the bolts don't come loose?
Last edited by Slamfire; 05-26-2015 at 10:07 PM.
