2007 Chrysler Pacifica coolant leak around timing cover - O-ring material questions

[92saturnsl2]

Subject vehicle is a 2007 Chrysler Pacifica 4.0L V6 w/ 195K miles. Started seeing drops on the garage floor which were clearly coolant (no other leaks).

At first glance I thought water pump as it was dripping from the bottom of the t-belt tensioner (which lives mostly inside the timing belt covers). On closer inspection it's further up and back where the REAR timing cover meets the engine block. I've since learned that there's three o-rings between the rear t-belt cover and engine block that seal coolant going in/out of the water pump. Never knew.

I'm fairly certain that's what I'll be dealing with (a bigger chore than just a timing belt job) but I can't find the two small O-rings -- completely discontinued. Mopar part #4483443. After more research, some resourceful folks on Mopar forums determined the dimensions match up with an off the shelf "219" O-ring. The 219 determines exact dimensions but not the material it's made of.

My choices: nitrile, EPDM, Viton and silicone seem most popular. I assume the original was nitrile perhaps but is there a better option for this application? Appreciate any insight. What you're looking at in the photos is the bottom/rear of the timing belt housing, the cast aluminum being the rear portion and the black sheet metal being the front cover.

 

[JohnnyG]

Ugh, McMaster Carr.
https://www.mcmaster.com/products/o-rings/
Pick your material.

 

[edhackett]

My choices: nitrile, EPDM, Viton and silicone seem most popular. I assume the original was nitrile perhaps but is there a better option for this application? Appreciate any insight. What you're looking at in the photos is the bottom/rear of the timing belt housing, the cast aluminum being the rear portion and the black sheet metal being the front cover.

It looks like BUNA-N(nitrile) is the best choice for hot water/ethylene glycol, followed by EPDM. Here's a basic reference that lists the best uses and not recommended applications for the various o-ring materials.

https://www.marcorubber.com/o-ring-material-quick-reference.htm

Ed

 

[92saturnsl2]

Thank you all for your help.

Seemed like nitrile and EPDM were the most appropriate options for water/coolant/steam. I chose EPDM as most of the nitrile options I was finding had a temperature limit of 212F. Hope it works out, lots of time required to get to the backside of the timing belt housing but I'll take that any day over removing a front cover to service a timing chain.

I chose a GMB timing belt kit (parts prices are crazy right now) and was surprised to find mostly OEM components inside. The only "GMB" parts were the water pump and tensioner pulley, which makes sense as they are a bearing company. The belt was Mitsuboshi and the the remainder were OEM, with the exact Mopar part # stamped on them.

The replacement GMB water pump on my '96 Maxima has been soldiering on for well over 100K now, so it was a decent gamble over spending $$$ on the expensive Continental / Gates / Dayco, etc.; you don't really know what you'll find in those either.

 

[Arc]

Thank you all for your help.

Seemed like nitrile and EPDM were the most appropriate options for water/coolant/steam. I chose EPDM as most of the nitrile options I was finding had a temperature limit of 212F. Hope it works out, lots of time required to get to the backside of the timing belt housing but I'll take that any day over removing a front cover to service a timing chain.

I chose a GMB timing belt kit (parts prices are crazy right now) and was surprised to find mostly OEM components inside. The only "GMB" parts were the water pump and tensioner pulley, which makes sense as they are a bearing company. The belt was Mitsuboshi and the the remainder were OEM, with the exact Mopar part # stamped on them.

The replacement GMB water pump on my '96 Maxima has been soldiering on for well over 100K now, so it was a decent gamble over spending $$$ on the expensive Continental / Gates / Dayco, etc.; you don't really know what you'll find in those either.

Dont forget about the torque around the gasket or o-rings. From experience I can say it's a bad feeling when you see it leaking again after all that work.

 

[The Critic]

If this is the o-ring you're looking for, I'd be happy to obtain one for you.

 

[paulo57509]

If you're looking outside of an OEM replacement, this reference is what I've been using since the 1980's. The file is downloadable. Relevant to this topic is Chapter 7.

https://test.parker.com/content/dam/Parker-com/Literature/O-Ring-Division-Literature/ORD-5700.pdf

 

[92saturnsl2]

If this is the o-ring you're looking for, I'd be happy to obtain one for you.

View attachment 310681

I appreciate the offer, how did you discover that one? Problem is I need two and $24.32ea is a tall ask for an O-ring. I have what (hopefully) is the same size EPDM O-ring being delivered from Grainger early next week. I have time for this repair, so if it doesn't look compatible I can source elsewhere and consider other options.

 

[Hohn]

It looks like BUNA-N(nitrile) is the best choice for hot water/ethylene glycol, followed by EPDM. Here's a basic reference that lists the best uses and not recommended applications for the various o-ring materials.

https://www.marcorubber.com/o-ring-material-quick-reference.htm

Ed

Cummins ranks EPDM higher than nitrile for coolant. Our engineering standards say to use EPDM for coolant.

It might be a difference diesel coolant formulations and gas engine formulations, though (SCAs generally don't exist in gas engine formulations).

 

[Hohn]

If you're looking outside of an OEM replacement, this reference is what I've been using since the 1980's. The file is downloadable. Relevant to this topic is Chapter 7.

https://test.parker.com/content/dam/Parker-com/Literature/O-Ring-Division-Literature/ORD-5700.pdf

This is the "bible" of O-ring seals. The overlap between this book and the respective Cummins engineering standards is suspiciously high (i.e. it's identical as far as I can tell).

 

[92saturnsl2]

Dont forget about the torque around the gasket or o-rings. From experience I can say it's a bad feeling when you see it leaking again after all that work.

Good advice! Will look up the torque specs for that back housing, it's what sandwiches the O-rings in place.

 

[The Critic]

I appreciate the offer, how did you discover that one? Problem is I need two and $24.32ea is a tall ask for an O-ring. I have what (hopefully) is the same size EPDM O-ring being delivered from Grainger early next week. I have time for this repair, so if it doesn't look compatible I can source elsewhere and consider other options.

Worldpac

Edit: it looks like some dealers may still have some:

 

[edhackett]

Cummins ranks EPDM higher than nitrile for coolant. Our engineering standards say to use EPDM for coolant.

It might be a difference diesel coolant formulations and gas engine formulations, though (SCAs generally don't exist in gas engine formulations).

Cummins is correct. The chart I posted is pretty basic and I got duped by the specific mention of ethylene glycol. The Parker reference is so much better at being able to fine tune a choice. Buna-N is the "good enough", might find it at the local hardware store choice. EPDM is the best choice.

Ed

 

[ElastomerGuy]

You might want to also consider HNBR. It's got very good chemical resistance and heat resistance. It's not inexpensive, though.

 

[ElectroMechanoMan]

EPDM or Viton. I use Viton for high temperature seals in air cylinders and control valves in hot environments. I have noticed that most of the belts and hoses in almost all new cars are EPDM. It is also used as liner material in progressive cavity pumps.

 

[92saturnsl2]

I should update this post in that I completed the repair, though it took much longer than I anticipated (mostly laziness, this being a spare car).

Getting the REAR timing belt housing off was a bear-- while I appreciate there's no oil to deal with in a timing belt equipped engine, it was still a process. Two bolts secured it from the side (front of vehicle) in areas that were difficult to access. At one point using "feel" to locate one of the said bolts, I managed to pull an A/C line off the compressor. Instant unintended refrigerant evacuation. Lots of cuss words thrown around during that event. The bolt I was looking for was very close by- only way to access it was by removing radiator fans, lower radiator hose to get in there.

Chrysler in their infinite wisdom, presses on the timing belt sprocket & crank pulley. The inner sprocket was "fun" getting removed and put back into the correct place, more curse words and new tools needed.

The rest was normal wrenching and though the timing belt service was premature because of these three O-rings, I'm confident with the work I've done-- replaced every seal (cams, crank, etc) I came across while I was in there-- It's completely leak free (after 1K miles or so); and should be a reliable vehicle for a good while longer. For a vehicle that cost me $5K eight years ago, I'm not complaining. It's a comfortable ride and a vehicle that's underrated in my opinion.