Radiator Help

surfdog4 · 09-21-2008, 06:43 PM

Well now i have a leaking radiator..has a crack in the plastic slightly below the upper hose connection

i'm having trouble understanding the different versions for sale..I see versions for the same years with No coolers, 1 cooler, and 2 coolers.

I have an '81 5-speed so i understand i don't need the transmission cooler, but is does "no cooler" mean it's some kind of core? i assumed from the PET that all the 928s had oil coolers

The '82 PET shows the same P/N for all the models, but the major suppliers show different numbers.

I'm also seeing "universal" units with two coolers but say they can be used with any system..true?

I've also seen someone who rebuilt a radiator with new plastic tanks and seals..anyone know the source of these parts? (not a fan of plastic but also not a fan of $1000 either)

Any advice would be appreciated..thanks

Danglerb · 09-21-2008, 09:22 PM

All my cars run the engine oil through a cooler on the left/driver side tank. Cars with an automatic tranny "may" use a right side cooler and/or an external cooler. If you don't need the cooler leave it plugged or just order the 5 spd version.

All the usual sources sell the Behr end tanks and will be able to tell you which you need, BUT if you don't have a local radiator shop that KNOWS the damn aluminum tabs it may be pointless to try.

What shape is your radiator in?

How old is it?

Does it have a known history of ALWAYS flushing and replacing coolant in the proper intervals (no more than every other year IMHO)?

A good new radiator is a lot of headache skipped, the edge I think goes to the C&R from 928Intl with welded end tanks etc.

surfdog4 · 04:02 AM

I have no history with this radiator, I'm assuming it's the original ('81). The crack is not at the top pipe but a few inches below..it was hard to figure out because it doesn't leak except when the engine is revved, so at idle you can see that it leaked but can't tell from where. I changed the coolant out when i first got the car and noticed it dropping some but a) wasn't running the car much and b) guessed it was still getting the air out. Just for fun i slapped some J-B weld over the crack but it also cracked (looks like the plastic is swelling under pressure)

I did notice when i changed the coolant that there was a trace of oil that settled in the bottom..but at the time i didn't really panic about it since the entire underside of the car was dripping oily slime (loose oil pan bolts) so i figured some might have dripped off into the drain pan. Also, the oil in the crankcase was not milky and i had no white smoke .

So now i'm thinking the oil cooler has a leak and the crack in the *(#&*# plastic end cap has me thinking the whole radiator is trash..but i saw a posting somewhere where someone replaced the plastic end caps so was wondering if that was a decent alternate. I've never seen the inside of one of these so have no idea how the piping is routed.

PS. DanglerB, thanks for the tip on the silicone spray for the spider hose couplings..i was using wheel bearing grease but silcone was easier..the bummer here is all the throttle body work got the car running great..so i was ready for some road trials until the radiator went kaputt

sjfarbs · 09-22-2008, 07:26 AM

The end caps can be replaced, usually the passenger side (US Model) is the one that will fail.

I had the same issue on my 84', the PO had used some JB weld to try and conceal it but once the pressure built up, whammo here comes the leak.

I was lucky to have a good RAD shop here with experience in German RAD's and the metal tabs.

I opted to replace just the failed side (passenger) and leave the drivers side alone (it was not leaking and upon searching the forum, found the drivers rarely fails).
My RAD has been fine ever since, but if I had an endless supply of money I would dump it into that nice Devek aluminum RAD

I would recommend pulling the RAD yourself as it is a painless job. Then you can really give it a good flush, it was amazing how much sand came pouring out of mine!!!

If you do pull it, make sure to counter hold the cooler lines, and also the elec plug at the front drivers side bottom of RAD, wouldn't want to yank it out will still plugged in

Danglerb · 09-22-2008, 08:59 AM

Chances of an 81 having "its" original radiator are about zero unless it has really low mileage etc. What is REAL common is that it has a used radiator out of some low mileage wrecked early 928 (the most scrapped kind).

The AT hose on my 84 parts car was impossible to remove. I sprayed it and worked on it for days, then cut the hose and took it to the radiator shop and they couldn't get it loose. Eventually one of Greg's mechanics got it off, but it was pure luck that nothing was damaged in the process.

Cooler is not part of the end tank, its a separate part. Remove the radiator yourself, shop labor to flush and change the tank maybe $100, something like $100 for each tank, no clue on the cooler cost, vs $1k for a new radiator.

How about using JBweld with some kind of patch to bridge the crack?

Fabio421 · 09-22-2008, 10:16 AM

I hear that all the cool kids are taking their radiators down and having replacement aluminum side tanks welded on. End of problem. If you go this route, please post before an after pics. I think I am about to embark on this task as well.

surfdog4 · 09-22-2008, 01:01 PM

thanks for the inputs..any idea how to check/fix the oil cooler if that is leaking? Guess I'll pull the radiator and see what i have

I thought about some sort of patch, i'm surprised J-B weld doesn't make some kind of epoxy with fibers in it for just such a problem.

The way that thing bulges out seems like you'd have to patch a really large area or get a really thick/stiff patch to prevent it from bulging completely..right now nothing to lose, of course!

thanks!

sjfarbs · 09-22-2008, 03:10 PM

I think you are on the right track, you need to pull it and see what you are dealing with.........bring to a RAD shop and have it pressure tested.

I suspect the plastic side tank on the passenger side is cracked.

If the cooler lines are a ***** to get out (mine were ansd sounds like dangler's were as well).
Just unclamp the hose and pull the hose off , then once it is out soak the crap out of it with PB or let the RAD shop deal with it.

Danglerb · 09-22-2008, 06:21 PM

Pressure testing the radiator and coolers was part of the flush at the radiator shop I went to.

I was thinking of a fitted sheet of aluminum as a patch, or stainless steel.

Sell that spare kidney on ebay and get a good radiator.

785sp · 09-22-2008, 07:08 PM

Hey Surfdog:

I would continue to go with the plastic end-caps. My radiator shop recommended it, saying in passing that it's good to have the end-caps be the weakest link. I didn't dwell too much on that comment, until about six months later when my thermostat froze and I overheaded quickly. My plastic end-cap blew off before my heads. Much cheaper.

surfdog4 · 09-23-2008, 07:19 AM

i had no idea those end caps were replaceable..do the radiator shops have them? .so i think i have two problems, (end cap leak and the oil cooler leaking) so think i will remove it and try and find a radiator shop.

Anybody in Baltimore/Washington/Annapolis area know of a shop that could possibly handle this?

(I'm quite fond of BOTH of my kidneys, dangler)

sjfarbs · 09-23-2008, 09:09 AM

Do not think a local RAD would stock that unless they work on 928's all the time.
Call Roger at 928's r us
817-430-2688
roger@************

He can get you set up with the plastic end tank.

Just a guess, I would not think the cooler would be leaking from the inside, I thought they were pretty bullet proof..............but maybe if someone wrenched the line into the cooler a bit too hard or without a counter hold, he could have buggered up the line.

Either way, the picture will be clear when you pull the RAD.

surfdog4 · 03:12 PM

well i do not have an oil cooler in the radiator...finally got back outside to take a look and there are no connections to the radiator where the manual shows the oil lines are..just the lower radiator hose. The A/C has a separate radiator in front of the main one.

I can't find any reference to this configuration in the manual, but i do see some of the replacement radiators are labeled "no coolers"..so i must not be the only one (UPDATE: i found out that US 80-83(?)) 5-speeds do not have oil coolers)

The really bad news then is that now I can only think the oil in my antifreeze is coming from something much worse inside the engine..cracked block?

I'll start the search here but anyone want to tell me where a tablespoon or so of oil could get into the antifreeze? I was hoping it was the oil cooler.

Between this and the radiator I am about to give up on this restoration

Charley B · 09-25-2008, 06:22 PM

If you have an internal mixing, let's hope it is a head gasket. It's time to do a compression test.

Danglerb · 09-25-2008, 08:19 PM

Oil in the coolant seems really odd.

surfdog4 · 04:54 PM

see below

surfdog4 · 10-12-2008, 04:55 PM

pulled the radiator yesterday...guess i will be shopping for an end tank.

...looking at that big gap there now i'm tempted to to have a run at the timing belt..how hard is it again?

surfdog4 · 10-12-2008, 06:09 PM

would a radiator from and 85 S fit in my '81? Somebody on ebay has one for sale, it has an oil cooler but i'm assuming i could just leave those open since i don't need them..might be a cheaper approach then getting my current one repaired

Danglerb · 10-12-2008, 06:56 PM

Just a fyi, the somebody is Surfridermason recently shut down on rennlist due to this new "business". People who have done business with him have had mixed results, not saying anything myself because I don't know anything, but I would proceed carefully and make absolutely sure of what was being purchased. It strikes me that he is much more knowledgeable about what 928Intl sells a part for, than what the part is, does, or its condition.

78 to 86 radiator should work in an 81 as long as you match the coolers etc., change occurred from 86 to 87 with the body style change I suspect.

surfdog4 · 04:29 AM

Thanks for the warning...it seemed obvious from the ebay ads that he is parting out an '85 "S"..and he has 8 feedbacks and already 1 negative.....part of me isn't too keen on buying a used radiator in that i might be in the same boat a little later..but if the bidding was really low it would be tempting..

The radiator he is selling has an oil cooler, mine has nothing, but i assumed i could just leave those connections open ...everybody else seems to sell "universal" replacements with oil and/or transmission coolers.

My plan "A" is to get the end tank from Roger and look for a shop locally that can attach it