Oil Leak 2.4 Dodge Caravan – Excessive Crankshaft End Play

DenLorsTools.com  Summary: Auto repair article about excessive crankshaft end-play on a 2007 Dodge Caravan with a 2.4 DOHC (Double Over Head Cam) 4cyl. engine. This type motor was most commonly used by Chrysler in Dodge Neons and more recently in PT Cruisers. Case study is on the cause of a rapid oil leak from the front crank seal, which ended up being from excessive crankshaft end play movement/float damaging the seal. Causes of thrust bearing damage discussed and suggestions on how to prevent this particular problem by using the correct tools. The old saying “Always use the the right tool for the job” proves to be right once again!

The 2007 Dodge Caravan with a 2.4 DOHC motor had engine oil pouring from the front crank shaft seal. Since it only had 50,000 miles on it - a replacement crankshaft seal, cam seals and timing belt seemed to be the correct plan of action. But after removing the front cover, belts and crank pulley, a different story unfolded. The crankshaft bolt was partially stripped as well as the crankshaft bolt threads. This means that someone Thrust Bearing didn’t use harmonic balancer installer on the pressed on pulley. Many times techs will just use a swing press (a big hammer) to get the pulley on far enough that the crank bolt can be used to press the harmonic balancer on all the way. Sometimes though, if only a few threads are grabbing the bolt and more importantly the crankshaft can be damaged. That’s the reason a harmonic balancer installer should be used.

The next problem found was that the timing belt sprocket was chipped by someone previously trying to pry it off. There’s 3 small bolt holes in the sprocket designed for a puller to be used when it is removed. Obviously the previous person working on the vehicle did not figure this out before breaking a small chunk of the sprocket by prying.

The ding pictured here, is more evidence that a hammer was used to install the harmonic balancer.

Staking or peening (with a center punch) is done when a seal seems to fit loosely or has walked out. The previous mechanic, or DIYer did not realize that the seal popping out was a symptom of a much larger problem. The REAL problem at this point is that there is entirely too much crankshaft end play or end float. The specifications allow for 10-15 thousandths of an inch end play or movement in and out. The end play measured with a dial indicator was .0050″ which will destroy the seal quickly if it walks or not.

Image shows 50 thousandths of an inch reading on the dial indicator.

Thrust bearings are usually bad when excessive end play is present. Usually vehicles that are equipped with an automatic transmission, this is NOT a common issue. Also if there was a problem on the transmission side, the stress would have been outward toward the front-side of the engine. Judging by the scuff marks left by the timing belt sprocket into the oil pump housing the stress was applied from the front towards the back-side of the engine. In this case it is most likely that improper installation of the harmonic balancer caused damage to the thrust bearings and possibly the crankshaft as well. The most likely cause of  Thrust Bearing damage in this case was due to improper harmonic balancer installation -  beating the crank pulley on with a big hammer!

Other Causes of thrust bearing damage.

1. Poor crankshaft surface finish, like damaged contact points prior to assembly.

2. Misaligned accessories causing a constant stress to be applied.

3. Lack of oiling, however problems with main bearings would most likely occur first.

4. Excessive torque converter pressure or swelling/ballooning.

5. Improper throw out bearing adjustment.

6. Driver riding the clutch pedal.

Incorrect torque converter installation may cause stress on the thrust bearing as well. However, if the torque converter is not fully engaged prior to transmission installation, the trans. pump housing is usually broken.