Freeze plugs?

gtmud · #1 02-16-2005, 07:31 AM

I have a 88 laredo 4.0, auto, 4x4 with an over heating problem. First it still has the "closed" system in it, but yesterday I noticed that there was coolant coming out of the lower portion on the bell housing of the tranny. There were no leaks anywhere,back of the head was dry, am I correct in thinking that I will have to pull the tranny back and I hope to find a leaking freeze plug, if there is indeed one back there? Any one else run into this problem, what is the easiest way to fix this. This XJ has 205K on it, runs fairly well, oil is still "clean" not mixing of coolant. Also the weird thing is after I "burped" the system the leak went away, but still had the heating problem.

SteveB05 · #2 02-16-2005, 07:39 AM

I don't know if there is a plug on the back of the 4.0 block.

When you "burped" the system, did you get it back to pressure again before looking for the leak? Does the cap hold its rated pressure? A bad cap is a cheap fix for an overheat sometimes.

If you have access to a pirometer (temperature probe), check the radiator temp at different places. Check for a major temp diference parallel to the tanks. This would indicate a plugged up radiator.

Also, a lean mixture and/or over-advanced timing would cause it to run hot as well.

gtmud · #3 02-16-2005, 08:10 AM

Thanks Steve, when I got this Xj it was overheating, the coolant that I flushed out was a tan/brown color, so I am certian that for one its in need of a through flushing and probably a replacement of the radiator. Its sort of my "project" vehicle(gotit for free) so when money allows I work on her.
Yes I did get it back to pressure. At least I think so, I could tell that there was coolant flowing, upper / lower rad hoses about the same temp.
To burp the system I took the upper hose off the T-stat, poured coolant into the rad. till there was a solid stream of coolant coming out of the T-stat housing. It ran for a good 15-30 minutes before it over heated. Running the heater helped bring it down a little but it was still high.
I figure that I am probably looking at replacing at least the W/P, RAD, T-stat,and all hoses.

Po Pilot · #4 02-16-2005, 03:36 PM

Quote:

Originally Posted by gtmud

Thanks Steve, when I got this Xj it was overheating, the coolant that I flushed out was a tan/brown color, so I am certian that for one its in need of a through flushing and probably a replacement of the radiator. Its sort of my "project" vehicle(gotit for free) so when money allows I work on her.
Yes I did get it back to pressure. At least I think so, I could tell that there was coolant flowing, upper / lower rad hoses about the same temp.
To burp the system I took the upper hose off the T-stat, poured coolant into the rad. till there was a solid stream of coolant coming out of the T-stat housing. It ran for a good 15-30 minutes before it over heated. Running the heater helped bring it down a little but it was still high.
I figure that I am probably looking at replacing at least the W/P, RAD, T-stat,and all hoses.

If you are going to go that far - change the closed system to an open one! If you are looking for a radiator the best one I have found (and others will agree) is a CSF 3-core. STAY AWAY FROM GDI!! Contact Dirk at http://www.dpgoffroad.com/ for the best price! If you can afford it a Hesco high output waterpump will aleviate any hot spots in the engine block and a bored out thermostat housing with high flow 195 t-stat ought to do the trick. If your freeze plugs are leaky then the whole system wont hold pressure and you will overheat! Also - you are overlooking one key component - the fan clutch. Replace it, more then likely its gone bad.

gtmud · #5 02-17-2005, 08:23 AM

Thanks Po Pilot,

I'll look into that radiator, they are about the same price as a new one for the closed system. But I still have a question. Can anyone tell me weather or not there is a freeze plug on the back of the 4.0, and if so, what is the best way to change them.

Po Pilot · #6 02-17-2005, 12:39 PM

Quote:

Originally Posted by gtmud

Thanks Po Pilot,

I'll look into that radiator, they are about the same price as a new one for the closed system. But I still have a question. Can anyone tell me weather or not there is a freeze plug on the back of the 4.0, and if so, what is the best way to change them.

There is a plug - three of them in a row on the right lower side of the engine block if you are looking at it from the front. The most rearward one is a pain in the ass to get to. I had to remove the engine mount to get to them all.

There isnt a plug on the backside of the block though. More then likely its leaking from the last plug and running back thru the tranny - mine was doing the same thing - most of the coolant was steaming off the exhaust downpipe leaving no trace on the ground.

gtmud · #7 02-18-2005, 07:56 AM

Thanks Po Pilot, I hope that I'll find a leaky freeze plug,versus a cracked block. I'll look at it this weekend, and keep my fingers crossed that its a "simple" fix. So far all I've bought for it is a battery. Thanks again for the info.

Po Pilot · #8 02-18-2005, 01:53 PM

Quote:

Originally Posted by gtmud

Thanks Po Pilot, I hope that I'll find a leaky freeze plug,versus a cracked block. I'll look at it this weekend, and keep my fingers crossed that its a "simple" fix. So far all I've bought for it is a battery. Thanks again for the info.

If it is indeed the plugs - then Napa has them.

Good luck!

gtmud · #9 02-18-2005, 05:36 PM

Hey PO Pilot,
I looked at her this afternoon, the freeze plugs looked good! Go figure, I replaced the oil pressure sender unit, found the engine cold is running about 50 psi. once its "warmed up" 25-30 psi. This is with running new straight SAE 30. As far as the temp issue, the weather here is about 45 degrees and windy, it took a while to get up to temp, then it started to climb. I hotwired the AUX fan and the temp came down right away and maintained 170-190 degree. I suspect a bad T-stat, and I need to find a fan shroud for the mechanical, or I thought about taking the mechanical off and installing a 14" electric instead which I have. So maybe I can get this over heat problem licked, and not spend more than $30. Of course all the hoses will need replaced.
If you have any other ideas let me know. Thanks,
Ken

Po Pilot · #10 02-21-2005, 03:48 PM

Quote:

Originally Posted by gtmud

Hey PO Pilot,
I looked at her this afternoon, the freeze plugs looked good! Go figure, I replaced the oil pressure sender unit, found the engine cold is running about 50 psi. once its "warmed up" 25-30 psi. This is with running new straight SAE 30. As far as the temp issue, the weather here is about 45 degrees and windy, it took a while to get up to temp, then it started to climb. I hotwired the AUX fan and the temp came down right away and maintained 170-190 degree. I suspect a bad T-stat, and I need to find a fan shroud for the mechanical, or I thought about taking the mechanical off and installing a 14" electric instead which I have. So maybe I can get this over heat problem licked, and not spend more than $30. Of course all the hoses will need replaced.
If you have any other ideas let me know. Thanks,
Ken

No signs of leakage around the plugs eh?

Nope - not a bad t-stat. If it were then the temp guage would have kept on climbing! I suspect that your mechanical fan clutch is gone since it took the AUX fan to reduce the temp. If you DONT have th4e shroud then your gonna get airflow that is all over the place and not directed at the radiator! Need to get that replaced as well!

gtmud · #11 02-22-2005, 03:04 PM

Thanks Po Pilot. I installed the 14" fan, found that there was no T-stat in the housing. So I drained the RAD., flushed out the block with water than put in some Super Flush (3-6 hour flush). Ran it, with the fans (Aux & 14") Temp stayed moderate, however I suspect the W/P is bad, due to bringing up the RPM (2K) and immediatly watching the temp go down. Oh installed a 195 temp stat. Now just to find the time to change the pump. Thanks for your help. Much appreciated.

Po Pilot · #12 02-22-2005, 03:37 PM

Quote:

Originally Posted by gtmud

Thanks Po Pilot. I installed the 14" fan, found that there was no T-stat in the housing. So I drained the RAD., flushed out the block with water than put in some Super Flush (3-6 hour flush). Ran it, with the fans (Aux & 14") Temp stayed moderate, however I suspect the W/P is bad, due to bringing up the RPM (2K) and immediatly watching the temp go down. Oh installed a 195 temp stat. Now just to find the time to change the pump. Thanks for your help. Much appreciated.

No t-stat? Holy Cripes! Someone was trying to solve the overheating problem the easy way! W/P isnt that big of a deal - if you can I would go with a HESCO high flow! Worth it! Glad to hear you are on your way. Anymore questions feel free to pm me!

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