IronicTonic

I recently purchased a 2001 C4 with just over 100k miles. The car has an excellent service record and everything appeared to be in great shape. Nothing major showed up on the PPI. It recently had the clutch and RMS done, no idea why they didn't do the IMS while they were in there too but I'm planning to install the LN IMS if I keep the car. I also have an aftermarket drive-train warranty that's good for 1 year.

After about 2 weeks of ownership and roughly 200 miles the car blew a coolant hose off. Fortunately I caught it and turned the engine off immediately so it didn't overheat. The dealer I purchased it at was very helpful and offered to fix it for free. They claimed the hose wasn't secured properly which is why it came loose. It was on the back side of the engine, not certain which hose it was.

Car was fixed and back on the road for another 2 weeks and 200+ miles and another hose blows off. This time it happened right as I was entering my neighborhood (good timing). I shut the engine off and coasted to my house. The dealer is offering to tow the car in again and fix it but I'm concerned they won't address the real issue, but just re-attach the hose again.

I have not had time to look into it further or have it towed because of my work schedule over the last 24 hours but I have several options and I'm hoping for some insight.

My question is, what would be the likely cause of a pressure buildup in the cooling system that causes hoses to pop off? Is this something I should dive into further to see if I can get it repaired under the warranty, which will not cover 100% of the cost, or should I have the dealer buy the car back (offer was already made)?

The car has not had any overheating issues, does not run hot, and does not have any unexplained coolant loss during operation. It just randomly blows the coolant lines off while driving. Could this be from a cracked cylinder liner? Head gasket?

I appreciate the assistance.

DBJoe996

Here is a suggestion - open the engine lid and find out which hose has come loose, or broke. No one can help you if we don't know which hose it is. You are assuming the worst and it is probably something simple. There are a number of coolant hoses around the engine bay with plastic connectors. At 100K those are old and brittle and break...often. Pictures help.

Macster

If the hoses really did come loose blow off from their connection this is either due to failed hose clamps -- failed due to age, corrosion, perhaps damage if they have ever been disturbed -- or due to having been disturbed not being properly installed/tightened.

My direct experience and my 2nd hand info is radiator hoses are long lived and and trouble free so your experience is to me unusual.

Excessive pressure build up should not occur but the pressure relief valve is in the coolant cap. Is the cap the correct cap? Not some aftermarket cap? The original caps would leak after a while. By original the one with the part number ending in "00". A new cap with a part number ending is "02" or "04" would be advised.

Check that both radiator fans come on. They come on when the A/C is switched on.

They also should come on when the coolant temperature gets too high and this in my experience is 212F. You can't know what the coolant temperature is from the gage. I used an ODB2 code reader/data viewer to monitor the coolant temp via the OBD2 port.

The fans should shut off as the coolant temp drops below 205F.

If the coolant temperature climbs higher, to (in my experience) 216F the fans should switch to high speed.

For both of my cars I have had one radiator fan fail and yet the coolant temperature was unaffected and A/C performance likewise was unaffected even in mid-90F ambient heat.

While I do not think there is a real problem with this car -- said without seeing the car, knowing any more than what I know based on what you wrote -- I can understand your concern. If the dealer is willing to buy it back at no loss to you might consider taking the dealer up on its offer. You and the car have gotten off on the wrong foot, through no fault of your own, and while over time this initial memory will fade if you can start over with another car you might be better off.

joe-1972

So sorry to hear about your troubles...
I also live in Naperville, if you need any help or someone to check over the car for you I would be glad to help if I can. I have a ODB2 dongle that we can use to check for the basic error codes and what temps your seeing... Let me know if you want me to swing by.

groovzilla

possible that previous owner or shop replaced these coolant hoses and didn't tighten the clamps properly? probably a good idea to see if hoses in question are replacements. check service records/contact previous owner

Byprodriver

The OE hose clamps are not meant to be reused, best to install high quality worm gear type clamps. If that doesn't fix the problem, pressure test coolant system. could be a cracked head.

5CHN3LL

One line blowing off is a fluke. Two blowing off is not coincidental in my book - I'd be looking long and hard at that engine. Maybe it IS a coincidence, but those are about as common as t*ts on a bull...

sweet victory

On a slight tangent...does warehouse 33 or pelican parts offer a hose & clamp replacement kit?

Wouldn't be a bad idea since a lot people are probably still on their original hoses and clamps.

IronicTonic

Thanks for the responses. I'm going to look into it further this weekend when I have the time.

Joe-1972-I appreciate the offer for help, I'll definitely let you know if I need anything.

I'll take a look at all of the hoses/clamps and likely replace the coolant cap. I have some type of aftermarket coolant cap (no brand listed, black color with white text) which could be part of the problem if it's not releasing excess pressure.

My intention is to get the motor checked out to be sure it's not something major. This would include a cooling system pressure test. If it turns out to be something major I'll probably take the dealers offer to buy back.

joe-1972

Aftermarket cap does not work well with the cooling system in our cars. Go factory correct and current revision... "04" I believe.
I had my car pressure tested after I had a radiator replaced and the F-ing thing was pissing like a pig... at least 6 different clamps gave way at the same time! No biggie, just clean off all the hoses and barb ends and replace with good worm type clamps. Refill and burp system a few times and your good to go.

Dont be shy of asking for help or an opinion... I should be free on Saturday but will be gone all day Sunday. Let me know if you need anything!

fpb111

Cap could very well be the problem. Should be blue part number, right on the cap, ending in 004 is the latest.

Barn996

You didn't mention what kind of 'dealer' sold you your Porsche. I'd ask to see the 1st and 2nd coolant hose that failed or wasn't properly secured. See if they let you look under your 911 while it's in the air to point out your coolant hose issues. How much can you recoup with their buy-back offer?

IronicTonic

It's a small used car dealer in my area that specializes in European cars. So far they have been very helpful. They did try to show me where the original coolant hose was located but it was difficult to see from the back hatch. The buyback offer was for 100% refund so zero loss if I take that route.

I like the car and the deal I got on it was tremendous. If it only needs a quick and simple fix then I plan to keep it.

groovzilla

next post....

groovzilla

tremendous deal from dealer can be scary words

there really isn't any such thing as a tremendous deal from a dealer. they usually know what they have and where to price it.

i'd get that buy-back in writing from the dealer before you proceed