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Topic: CAT Blow By Kit

Posted By: keepingthelightson on 06/18/11 11:57pm

Are any of you using a closed crankcase ventilation kit made by Racor (CCV4500) to resolve this blow by tube problem? It is designed to allow the air and oil back into the engine rather than blowing the oil out on the highway (or in my case all over the toad). I am considering the kit. I just returned from a 3K trip and my car needed washing throughout the trip.


05 Tiffin Phaeton 40 QDH w/4 slides
CAT C7 350+ HP MP-8, Aero Muffler, AFE Filter
06 HHR LT Toad
Ready Brute Elite

Posted By: tinkerer on 06/19/11 06:49am

Off the subject, but are you sure you are not overfilling your Cats oil pan. On my C7 I fill it with exactly the amount (19 qts) my Cat manual suggest. That fills it to the add mark on the dipstick, obviously the dipstick is off.

Posted By: wolfe10 on 06/19/11 07:11am


That is NOT off the subject. Overfilling is the reason for over 80% of blow by issues-- not just on Caterpillar, but on any diesel engine with open crankcase ventilation.

Call the Caterpillar RV Hotline with your engine serial number to verify the correct oil quantity (more current information than your owners manual) and then calibrate your engine oil dipstick to that quantity.

Do this and then verify that you still have a problem before spending money on something you may not need.

Brett Wolfe
2003 Alpine 38'

FMCA Forum:

Diesel RV Club:

Posted By: jauguston on 06/19/11 09:53am

Your engine is amost surely overfilled with oil. CAT engines are furnished to the chassis builders without dipsticks and dipstick tubes. The chassis builders furnish them in my case Freightliner. Umproper length dipsticks is a known issue with 3126 and C-7 CAT engines. The dipstick needs to be calibrated. Mine was such that it took 24 quarts to reach the full mark when the actual capacity is 19 quarts including 2 quarts for the filter. The first time I pulled a mountain pass I completely covered my Samurai with a gallon of oil. We had put about 2000 miles on it since we bought it used but all our driving had been on fairly level roads.

To calibrate the stick drain the oil and refill 14 quarts and mark the stick ADD. Add three more quarts and mark the stick FULL. With a new filter start the engine and run it for several minutes then add two more quarts for a total of 19 quarts. These instructions do NOT apply to engines with the deep cast aluminum pan.

The slobber tube should extend back past the radiator on rear radiator coaches. That blowby kit is not needed.

You will find a lot of discussion about this issue on the Forum older posts.


* This post was edited 06/19/11 10:02am by jauguston *

2005 Coachman Sportscoach Elite 402 40'
350hp Cat C-7 w/MP-8
7500w Onan quiet diesel generator
6-Kyocera 130w solar panels SB3024i MPPT controller
Pressure Pro TPMS
1987 Suzuki Samurai tintop Toad w/VW 1.6 turbo diesel power

Posted By: keepingthelightson on 06/19/11 12:37pm

Hey guys,
Thanks for the responses. Nope 19qts. is what I put in prior to leaving on vacation. Any other ideas?


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