driving without radiator cap

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Oct 12, 2010
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Edmond, OK
Picked up my daughters 03 lx470 last night from dealership where it had the ECU recall done (airbags,) and was going through the $2400 worth of recommended service that needed to be done. They suggested new wipers that they would replace for $66 and new radiator cap that would run me $103 ($63 for labor to twist it to the left, open package and twist new one to the right.) Well, I wanted to see with my own eyes the damage to the radiator cap so I popped the hood and noticed that it was gone. Just an open radiator top and what appeared to be dried coolant spewed all over the engine. I looked around and found the original cap down by the battery. Thankfully it didn't get into fan or belts or something that could have really done some damage.

I have called the dealership and asked them to note that cap was removed and not put back on in case there is an issues in the future that could be explained by the cap being off as I drove it 15 miles down the highway to our house. I didn't notice any overheating or other issue. What should I watch for in the future? Is there anything that could be caused by this I should have checked out? Dealership said they would top off fluid and clean the engine bay, but not sure its worth the time to drive it back over there just for that.

And, what should I see on a bad cap? Do they need to be changed periodically "just because?"
 
It's a pressure regulation device and indeed worth changing periodically. I'll replace the cap if replacing all the hoses for example or when installing a new radiator.

I think I can usually DIY it for a lot less than $103 ;) and mine usually stays where I put it.
 
I'm assuming that they simply did not attach the radiator cap correctly and you do not have some serious engine issue that blew the cap off. If the truck ran fine on the way home I would very surprised you wouldn't have noticed. If that is the case I wouldn't worry about it too much other than the mess. The cooling system will not have been able to build pressure and cooling capacity would be very reduced but as long as the truck did not overheat you should not have an issue.

There is a possibility you got some contaminant in the coolant in the short drive home but personally I would not at all be concerned about dirt, water, etc getting in there from those amount of miles.

I would note how much coolant it takes to fill the radiator, I am willing to bet not much, and I would monitor the temp gauge for the next few trips other than that I would not be concerned.

Radiator caps do go bad. I have had bad luck with aftermarket ones on all my vehicles (Ford, Jeep, Toyota) so I usually go OEM. In my garage they get changed when water pumps (timing belt service) or radiators get replaced.
 
Take it to them and have them top it off and replace the cap for FREE. After quoting a price like that and showing they can't even put yours back on correctly is weak. The end cost to them will be like 10-15 bucks.
 
I would drive back on the spot and make them clean it in my presence, and watch. The filth that would come from my mouth would embarrass everyone in earshot of the service writer. I would demand to stand 5 feet off the grill and just watch. Any money I paid them I would dispute with whomever.

In the very words or a lexus manager, this is lexus, we don't do that. But in the end, they all do that.
 
As to your original question, get a decent radiator pressure tester, which will also include an adapter to test the cap. I usually replace mine when I replace the cooling system thermostat. There's no direct correlation, other than both have a spring and rubber seal. It's just an easy way for me to remember.
 
Thanks everyone, my regular guy has it now to replace the steering rack, for the third time in a year and a half, and he said he couldn't find any issues from overheating or anything.
On another note NEVER BUY FROM AUTOZONE!
 
Thanks everyone, my regular guy has it now to replace the steering rack, for the third time in a year and a half, and he said he couldn't find any issues from overheating or anything.
On another note NEVER BUY FROM AUTOZONE!

Yup! I only buy my parts from Camelback (Toyota OEM) or CruiserOutfitters.com. AutoZone is for bulbs and wiper blades only IMO.
 
Previous owner bought the rack there with lifetime warranty. His help and that warranty has saved me some money, but I would rather have a quality rack and pay more one time. @cruiseroutfit is great. Kurt and everyone there is very knowledgeable. I will check out Camelback. Thanks
 
Sometimes i get lazy and think i might pay someone to do some maintenance on my trucks. Short of time or space. Stories like this just keep me motivated to continue to do my own work.
 
Quick anecdote: Wife took our Subaru skiing for the day at Winter Park, up over Berthoud Pass.

While en route, car went nuts and lost brakes, etc. She pulled over and we discussed via phone. Not knowing first hand the situation, we opted to have her towed back to town. Subaru's are known to blow gaskets around 100K miles - we're at 95K. Really didn't know how badly a situation it might've become and was bracing for an expensive repair. There was no prior warning.

Shop takes a look at it - low and behold, the radiator cap completely fell apart. Thus causing the coolant to drop out and said symptoms on the road. They replaced it, filled/burped the coolant and ... back to normal.

Easy, regular $15 fix on most cars and worth scheduling via Amazon delivery. Lesson learned
 
Not likely you blew the cap or radiator neck of from pressure. Likely mechanic was distracted and forget to put on the new cap. It happens!

Old cap was likely sitting to side on top of radiator. As your drove cap slid over to battery area. It happens often!

As you drove the system heated and coolant expanded, expanding out of radiator goose neck. Fan and air flow, while driving, likely through coolant back around engine making a mess. No big deal. Idler bearing & tension bearing with old weak dust/water seals, may now squeal from moisture in bearings. If so replace them. Rubber of belt doesn't like coolant. So if soak consider replacing if it squeals.

As coolant level dropped, it may have dropped so low temp sending unit was out of coolant. This gives false read on gauge that engine is running cool. The risk here is over-heating, while gauge gives false cool running reading. The heads "MAY" (not will) warp if temp gets to high. I doubt your head(s) wrap from overheating in this case. But I don't know how long 15 miles took you, OAT or traffic condition (black top, stop and go we run very hot).

Now with new rad cap, make sure your coolant system is topped. Check each morning (best with front of vehicle higher than rear) under cap, after 8 hour cool down. Fill to the top of neck. Fill reservoir about half way at same time.

If head or heads wrapped. Head gasket will likely then be leaking coolant. So watch you coolant level closely. Be aware; ambient temp (OAT) will change coolant level in reservoir. i.e: at 20 f reservoir may be very low looking, at 80 F may be look very high.

Head gasket can be visually inspected for leaks (pink crusty). You can also request a coolant pressure test be done long term (over night).
 
I would take it back over there and have them write a repair order for it at least. So there is a record of it.
 
Sounds like you owe them $21. They obviously completed a third of that labor by turning it to the left. Hahaha

Sorry, had to throw in my stupid sarcastic humor.
 
Sometimes i get lazy and think i might pay someone to do some maintenance on my trucks. Short of time or space. Stories like this just keep me motivated to continue to do my own work.
yep. I wish I had the knowledge to do all the work folks on this forum know how to do. I hate paying for something I think I should be able to fix.
 
yep. I wish I had the knowledge to do all the work folks on this forum know how to do. I hate paying for something I think I should be able to fix.

All you have to do is try for the most part. Almost everything you can do is well described in multiple threads. Biggest obstacle is a place to work. I guarantee you do better than most cheap shops.
 
I would take it back over there and have them write a repair order for it at least. So there is a record of it.
I can definitely do this. Repair order for radiator cap/coolant level?
 
I started doing my own repair when I saw a guy from high school working at an independent shop....
I wouldn't let that guy pull weeds from my yard let alone work on a car.
 

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